ObsEva (OBSVF) 20-F 9 Mar 18 2017 FY Annual report (foreign) Financial data

Document and Entity Information

Document and Entity Information	12 Months Ended
	Dec. 31, 2017shares
Document And Entity Information [Abstract]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	OBSV
Entity Registrant Name	OBSEVA SA
Entity Central Index Key	1,685,316
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding	37,131,262

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 110,841	$ 25,508
Other receivables	783	783
Prepaid expenses and deferred costs	1,490	2,415
Total current assets	113,114	28,706
Non-current assets
Furniture, fixtures and equipment	323	121
Intangible assets	21,608	16,608
Other long-term assets	190	90
Total non-current assets	22,121	16,819
Total assets	135,235	45,525
Current liabilities
Other payables and current liabilities	2,865	2,383
Accrued expenses	6,514	4,269
Total current liabilities	9,430	6,652
Current tax liability	51
Non-current liabilities
Post-employment obligations	3,099	2,832
Other long-term liabilities	55
Total non-current liabilities	3,154	2,832
Shareholders’ equity
Share capital	2,864	1,740
Share premium	219,335	71,966
Reserves	7,119	1,934
Accumulated losses	(106,667)	(39,599)
Total shareholders’ equity	122,651	36,041
Total liabilities and shareholders’ equity	$ 135,235	$ 45,525

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Comprehensive Income [Abstract]
Operating income other than revenue	$ 16	$ 22	$ 17
OPERATING EXPENSES
Research and development expenses	(54,912)	(23,711)	(16,892)
General and administrative expenses	(12,568)	(6,452)	(2,954)
Total operating expenses	(67,480)	(30,163)	(19,846)
OPERATING LOSS	(67,464)	(30,141)	(19,829)
Finance income	590	36
Finance expense	(1)	(97)	(38)
NET LOSS BEFORE TAX	(66,875)	(30,202)	(19,867)
Income tax expense	(51)
NET LOSS FOR THE YEAR	$ (66,926)	$ (30,202)	$ (19,867)
Net loss per share
Basic	$ (2.25)	$ (1.40)	$ (1.87)
Diluted	$ (2.25)	$ (1.40)	$ (1.87)
Items that will not be reclassified to profit and loss
Remeasurements on post-employment benefit plans	$ (142)	$ (599)	$ (1,356)
Items that may be reclassified to profit or loss
Currency translation differences		(83)	(128)
TOTAL OTHER COMPREHENSIVE LOSS	(142)	(682)	(1,484)
TOTAL COMPREHENSIVE LOSS FOR THE YEAR	$ (67,068)	$ (30,884)	$ (21,351)

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Cash Flows [Abstract]
NET LOSS BEFORE TAX FOR THE YEAR	$ (66,875)	$ (30,202)	$ (19,867)
Adjustments for:
Depreciation	70	46	36
Post-employment cost / (benefit)	7	(384)	57
Share-based payments	8,856	2,237	3,268
Finance (income) / expense, net	(589)	61	38
(Increase) / decrease in other receivables		(714)	4
Decrease / (increase) in prepaid expenses, deferred costs and other long term-assets	721	(2,033)	273
Increase in other payables and current liabilities	399	1,788	155
Increase in accrued expenses and other long-term liabilities	1,696	612	2,125
NET CASH FLOWS USED IN OPERATING ACTIVITIES	(55,715)	(28,589)	(13,911)
Payments for plant and equipment	(189)	(45)	(50)
Acquisition of a license	(5,000)		(10,000)
NET CASH FLOWS USED IN INVESTING ACTIVITIES	(5,285)	(45)	(10,050)
Proceeds from issues of shares	156,786	46	75,836
Payment of share issuance costs	(11,042)	(33)	(1,433)
Payment of deferred costs of financing activities		(206)
Interests paid	(1)	(8)
Interests received		34	1
NET CASH FLOWS FROM / (USED IN) FINANCING ACTIVITIES	145,743	(167)	74,404
Net increase / (decrease) in cash and cash equivalents	84,743	(28,801)	50,443
Cash used for rental deposits	(96)
Cash and cash equivalents as at January 1,	25,508	54,275	4,008
Effects of exchange rate changes on cash and cash equivalents	590	34	(176)
Cash and cash equivalents as at December 31,	$ 110,841	$ 25,508	$ 54,275

Consolidated Statement of Chang

Consolidated Statement of Changes in Equity - USD ($) $ in Thousands	Total	Share capital [Member]	Share premium [Member]	Share-based payments reserve [Member]	Foreign currency translation reserve [Member]	Total reserves [Member]	Accumulated losses [Member]
Beginning Balance at Dec. 31, 2014	$ 5,987	$ 764	$ 23,255	$ 460	$ (278)	$ 182	$ (18,214)
Loss for the year	(19,867)	0	0	0	0	0	(19,867)
Other comprehensive loss	(1,484)	0	0	0	(128)	(128)	(1,356)
TOTAL COMPREHENSIVE LOSS FOR THE YEAR	(21,351)	0	0	0	(128)	(128)	(21,223)
Capital contribution	75,823	915	77,286	(2,378)	0	(2,378)	0
Share issuance costs	(1,433)	0	(1,433)	0	0	0	0
Issuance of non-voting shares	15	15	489	(489)	0	(489)	0
Acquisition of license	2,366	0	0	2,366	0	2,366	0
Share-based remuneration	3,268	0	0	3,268	0	3,268	0
Ending Balance at Dec. 31, 2015	64,675	1,694	99,597	3,227	(406)	2,821	(39,437)
Loss for the year	(30,202)	0	0	0	0	0	(30,202)
Other comprehensive loss	(682)	0	0	0	(83)	(83)	(599)
TOTAL COMPREHENSIVE LOSS FOR THE YEAR	(30,884)	0	0	0	(83)	(83)	(30,801)
Issuance of shares - IPO		26	2,366
Share issuance costs	(33)	0	(33)	0	0	0	0
Issuance of non-voting shares	20	20	675	(675)	0	(675)	0
Acquisition of license	26	26	2,366	(2,366)	0	(2,366)	0
Share-based remuneration	2,237	0	0	2,237	0	2,237	0
Offset of accumulated losses with share	0	0	(30,639)	0	0	0	30,639
Ending Balance at Dec. 31, 2016	36,041	1,740	71,966	2,423	(489)	1,934	(39,599)
Loss for the year	(66,926)	0	0	0	0	0	(66,926)
Other comprehensive loss	(142)	0	0	0	0	0	(142)
TOTAL COMPREHENSIVE LOSS FOR THE YEAR	(67,068)	0	0	0	0	0	(67,068)
Issuance of shares - IPO	96,750	496	96,254	0	0	0	0
Issuance of shares - PIPE	60,000	592	59,408	0	0	0	0
Issuance of shares - Incentive Plan	36	36	3,671	(3,671)	0	(3,671)	0
Share issuance costs	(11,964)	0	(11,964)	0	0	0	0
Share-based remuneration	8,856	0	0	8,856	0	8,856	0
Ending Balance at Dec. 31, 2017	$ 122,651	$ 2,864	$ 219,335	$ 7,608	$ (489)	$ 7,119	$ (106,667)

General information

General information	12 Months Ended
	Dec. 31, 2017
Disclosure Of General Information About Financial Statements [Abstract]
General information	1. General information ObsEva SA (the “Company”) was founded on November 14, 2012, and its address is 12 Chemin des Aulx, 1228 Plan-les-Ouates, Geneva, Switzerland. The terms “ObsEva” or “the Group” refer to ObsEva SA together with its subsidiaries included in the scope of consolidation (note 2.2). The Group is focused on the development and commercialization of novel therapeutics for serious conditions that compromise women’s reproductive health and pregnancy. The Group has a portfolio of three mid- to late-stage development in-licensed compounds (OBE2109, nolasiban and OBE022) being developed in four indications. The Group has no currently marketed products. These consolidated financial statements are presented in dollars of the United States (USD), rounded to the nearest thousand, except share and per share data, and have been prepared on the basis of the accounting principles described in note 2. These consolidated financial statements were authorized for issue by the Company’s Board of Directors (the “Board of Directors”) on March 9, 2018.

Accounting principles applied i

Accounting principles applied in the preparation of the consolidated financial statements	12 Months Ended
	Dec. 31, 2017
Disclosure Of Accounting Policy [Abstract]
Accounting principles applied in the preparation of the consolidated financial statements	2. Accounting principles applied in the preparation of the consolidated financial statements 2.1 Basis of preparation These consolidated financial statements have been prepared in accordance with the International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). The consolidated financial statements are based on a historical cost basis. The preparation of financial statements in conformity with IFRS requires the use of certain critical accounting estimates. It also requires management to exercise its judgement in the process of applying the Group’s accounting policies. The areas involving a higher degree of judgement or complexity, or areas where assumptions and estimates are significant to the consolidated financial statements, are disclosed in note 2.5. Due to rounding, numbers presented throughout these consolidated financial statements may not add up precisely to the totals provided. All ratios and variances are calculated using the underlying amount rather than the presented rounded amount. 2.2 Scope of consolidation Subsidiaries are all entities over which the Group has control. The Group controls an entity when the Group is exposed to, or has rights to, variable returns from its involvement with the entity and has the ability to affect those returns through its power to direct the activities of the entity. Subsidiaries are fully consolidated from the date on which control is transferred to the Group. They are deconsolidated from the date that control ceases. The Company currently consolidates the financial operations of its two fully-owned subsidiaries, ObsEva Ireland Ltd, which is registered in Cork, Ireland and organized under the laws of Ireland, and ObsEva USA Inc., which is registered and organized under the laws of Delaware, USA. ObsEva Ireland Ltd had no operations and no results of operations to report as of December 31, 2017 and 2016. ObsEva USA Inc. had no operations and no results of operations to report as of December 31, 2016. 2.3 Standards and interpretations published by the IASB The IASB and the International Financing Reporting Standards Interpretations Committee have recently issued new standards and interpretations to be applied to the Group’s consolidated financial statements. No new standards and amendments applied by the Group in 2017 had an impact on its consolidated financial statements. In 2018, the Group will adopt the following new relevant standards: IFRS 9 Financial Instruments, effective on January 1, 2018, with early adoption allowed In July 2014, the IASB issued IFRS 9 Financial Instruments Financial Instruments: Recognition and Measurement IFRS 15 Revenue from Contracts with Customers, effective on January 1, 2018, with early adoption allowed In May 2014, the IASB issued IFRS 15 Revenue from Contracts with Customers Construction Contracts Revenue In 2019, the Group expects to adopt the following new relevant standards: IFRS 16 Leases, effective for annual periods beginning on or after January 1, 2019 In January 2016, the IASB issued IFRS 16 Leases Leases Other new standards and amendments published but not yet effective will have no material impact on the consolidated financial statements of the Group. 2.4 Significant accounting policies Current assets Other receivables and other current receivables or prepayments are carried at their nominal value. Individual receivables that are known to be uncollectible are written off by reducing the carrying amount directly. The Group considers that there is evidence of impairment if any of the following indicators are present: • significant financial difficulties of the debtor; • probability that the debtor will enter bankruptcy or financial reorganization; and • default or delinquency in payments (more than 30 days overdue). Receivables for which an impairment provision was recognized are written off against the provision when there is no expectation of recovering additional cash. Furniture, fixtures and equipment Furniture, fixtures and equipment are carried at cost less depreciation and impairment. Historical cost includes expenditure that is directly attributable to the acquisition of the items. Depreciation is calculated using the straight-line method, on the basis of the following useful lives: • furniture 5 years • hardware 3 years • leasehold improvement duration of lease Furniture, fixtures and equipment are reviewed for impairment whenever events or changes in circumstances indicate that their carrying amount may not be recoverable, on an individual basis. An impairment loss is recognized for the amount by which the asset’s carrying amount exceeds its recoverable amount. The assets’ residual values and useful lives are reviewed, and adjusted if appropriate, at the end of each reporting period. Intangible assets Separately acquired patents, licenses and other intangible assets are recorded at historical cost and subsequently measured at cost less accumulated amortization and any impairment losses. The acquisition of certain intangible assets, mainly licenses, may involve additional payments contingent on the occurrence of specific events or milestones. Unless the Group already has a present obligation to make the payment at a future date, the initial measurement of the intangible asset does not include such contingent payments. Instead, such payments are subsequently capitalized as intangible assets when the contingency or milestone occurs. Estimated useful life is the lower of legal duration and economic useful life, which does not exceed 20 years. The estimated useful life of the intangible assets is annually reviewed, and if necessary, the future amortization charge is accelerated. For licenses, the amortization starts when the assets become available for use, generally once proper regulatory and marketing approval are obtained. Intangible assets are subject to impairment testing annually, and whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Post-employment benefits Group companies operate various pension schemes. All employees of ObsEva SA participate in a retirement defined benefit plan. A defined benefit plan is a pension plan that defines an amount of pension benefit that an employee will receive on retirement, usually dependent on one or more factors such as age, years of service and compensation. The liability recognized in the balance sheet in respect of defined benefit pension plans is the present value of the defined benefit obligation at the end of the reporting period less the fair value of plan assets. The defined benefit obligation is calculated annually by an independent actuary, using the projected unit credit method. The present value of the defined benefit obligation is determined by discounting the estimated future cash outflows using interest rates of high-quality corporate bonds that are denominated in the currency in which the benefits will be paid, and that have terms to maturity approximating to the terms of the related pension obligation. Actuarial gains and losses arising from experience adjustments and changes in actuarial assumptions are charged or credited to equity in other comprehensive income in the period in which they arise. Past-service costs are recognized immediately in the consolidated statement of comprehensive loss. During 2017, ObsEva USA, Inc established a 401K, defined contribution plan, for the employees of the company. A defined contribution plan is a pension plan under which the amounts paid by the employer are fixed in advance. The plan assets are held by a third party custodian. ObsEva USA, Inc. contributions to the defined contribution plan are charged to the income statement as incurred. The Group has no further obligation once the contributions have been paid. Equity Incremental costs directly attributable to the issuance of common shares and options are recognized as a deduction from equity, net of any tax effects. Research and development Research expenses are charged to the consolidated statement of comprehensive loss as incurred. Development expenses are capitalized as intangible assets when it is probable that future economic benefits will flow to the Group, and the following criteria are fulfilled: • it is technically feasible to complete the intangible asset so that it will be available for use or sale; • management intends to complete the intangible asset and use or sell it; • there is an ability to use or sell the intangible asset; • adequate technical, financial and other resources to complete the development and to use or sell the intangible asset are available; and • the expenditure attributable to the intangible asset during its development can be reliably measured. In the opinion of management, due to uncertainties inherent in the development of the Group’s product candidates, the criteria for development costs to be recognized as an asset as defined by IAS 38 Intangible Assets Foreign currencies Functional and presentation currency Items included in the consolidated financial statements of the Group are measured using the currency of the primary economic environment in which each Group’s entity operates (the “functional currencies”). Until December 31, 2016, the functional currency of the Company was the Swiss franc (CHF). As from January 1, 2017, due to a change of its primary economic environment, the functional currency of ObsEva SA became the US dollar (USD), which is also the functional currency of ObsEva USA, Inc. and the presentation currency of the Group. Transactions and balances Foreign currency transactions are translated into the functional currency using the exchange rates at the dates of the transactions or valuation where items are re-measured. Foreign exchange gains and losses resulting from the settlement of such transactions and from the translation of monetary assets and liabilities denominated in foreign currencies at year end exchange rates are recognized in profit or loss. Foreign exchange gains and losses that relate to borrowings are presented in the consolidated statement of comprehensive loss, within finance costs. All other foreign exchange gains and losses are presented in the consolidated statement of comprehensive loss on a net basis within other income or other expenses. Translation into the presentation currency until December 31, 2016 The results and financial position of operations that had a functional currency different from the presentation currency were translated into the presentation currency as follows: • assets and liabilities were translated at the exchange rate prevailing on December 31 of each year; • income and expenses were translated at average exchange rates; and • all resulting exchange differences were recognized in other comprehensive income. The following rates have been used for the translation from the functional currency to the presentation currency: Income statement Balance sheet Average rate (CHF) Closing rate as of December 31, (CHF) 2016 2015 2016 2015 USD 0.9850 0.9624 1.0160 1.0010 Share-based compensation The Group operates two equity incentive plans. A share-based, equity-settled, plan was formally set-up by the Group in 2013 (the “2013 EIP”). Participants eligible for awards under the 2013 EIP are executives, directors, employees, agents and consultants. The fair value of the shares granted under the 2013 EIP is determined at each grant date by using either an option pricing method that uses a Black-Scholes model or a hybrid method, as appropriate, both based on a combination of the discounted cash flow method, under the income approach, and the backsolve method. A share-based, equity-settled, plan was formally set-up by the Group in 2017 (the “2017 EIP”). Participants eligible for awards under this plan are executives, directors, employees, agents and consultants. The fair value of the stock-options granted under the 2017 EIP is determined at each grant date by using a Black-Scholes model. When the equity instruments granted do not vest until the counterparty completes a specified period of services, the Group accounts for those services as they are rendered by the counterparty, during the vesting period, with a corresponding increase in equity. Deferred income taxes Deferred income tax is provided in full, using the liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the consolidated financial statements. However, if the deferred income tax arises from initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit and loss, it is not accounted for. Deferred income tax is determined using tax rates and laws that have been enacted or substantively enacted by the balance sheet date and are expected to apply when the related deferred income tax asset is realized or the deferred income tax liability is settled. Deferred income tax assets are recognized to the extent that it is probable that future taxable profit will be available against which the temporary differences can be utilized. Leases Leases of assets under which all the risks and rewards of ownership are effectively retained by the lessor are classified as operating leases, and payments made are charged to the statement of comprehensive loss on a straight-line basis. Segment information The Group operates in one segment, which is the research, development of innovative women’s reproductive, health and pregnancy therapeutics. The marketing and commercialization of such therapeutics depend, in large part, on the success of the development phase. The Chief Executive Officer of the Company reviews the consolidated statement of operations of the Group on an aggregated basis and manages the operations of the Group as a single operating segment. The Group currently generates no revenue from the sales of therapeutics products. The Group’s activities are not affected by any significant seasonal effect. The geographical analysis of non-current assets is as follows: As at December 31, in USD ‘000 2017 2016 Switzerland 21,832 16,819 USA 289 — Total non-current assets as at December 31 22,121 16,819 The geographical analysis of operating expenses is as follows: Year ended December 31, in USD ‘000 2017 2016 2015 Switzerland 63,956 30,163 19,846 USA 3,524 — — Total operating expenses 67,480 30,163 19,846 2.5 Critical accounting estimates and judgments Estimates and judgments are continually evaluated and are based on historical experience and other factors, including expectations of future events that are believed to be reasonable under the circumstances. Critical accounting estimates and assumptions The Group makes estimates and assumptions concerning the future. The resulting accounting estimates will not necessarily equal to related actual outcome. The following areas involve a higher degree of judgement or complexity or are areas where assumptions and estimates can have a significant impact on the consolidated financial statements: • Post-employment obligations: the actuarial valuation involves making assumptions about discount rates, future salary increases, mortality rates and future pension increases. Due to the long-term nature of these plans, such estimates are subject to significant uncertainty (note 10); • Share-based compensation: the determination of the fair value of the equity instruments granted involves the use of certain assumptions subject to judgement (note 18); • Commencement of depreciation and amortization: the depreciation and amortization starts when the assets are available for use in the manner intended by management, which requires judgement (notes 7 and 8); • Research and development costs: the Group recognizes expenditure incurred in carrying out its research and development activities until it becomes probable that future economic benefits will flow to the Group, which results in recognizing such costs as intangible assets, involving a certain degree of judgement (note 13); • Deferred taxes: the recognition of deferred tax assets requires assessment of whether it is probable that sufficient future taxable profit will be available against which the deferred tax assets can be utilized (note 16); • Impairment of assets: as part of impairment tests, the recoverable amounts of tested assets have been determined based on fair value calculations requiring the use of certain assumptions, subject to judgement (note 8); • Changes in functional currency: the determination of the functional currencies of Group’s companies based on the primary economic environment of each entity requires a certain degree of judgement from management.

Financial risk management

Financial risk management	12 Months Ended
	Dec. 31, 2017
Financial Risks Management [Abstract]
Financial risk management	3. Financial risk management 3.1 Financial risk factors The Group’s activities expose it to a variety of financial risks such as foreign exchange risk, credit risk, interest rate risk and liquidity risk. The Group’s overall risk management program focuses on the unpredictability of financial markets and seeks to minimize potential adverse effects on the Group’s financial performance. Financial risk management is carried out by the Group`s finance department subject to and pursuing policies approved by the Board of Directors. Foreign exchange risk The Group operates internationally and is exposed to foreign exchange risk arising from various currency exposures, primarily with respect to the Swiss franc (CHF), Euro (EUR) and British Pound (GBP). Foreign exchange risk arises from future commercial transactions (e.g. costs for clinical services) and recognized assets and liabilities. Management has set up a policy to manage the foreign exchange risk against their functional currency. To manage its foreign exchange risk arising from future commercial transactions and recognized assets and liabilities, the Group’s finance department maintains foreign currency cash balances to cover anticipated future requirements. The sensitivity of profit or loss to changes in the exchange rates in the reported periods are as follows: EUR positions Increase /decrease exchange rate vs CHF (2016) and USD (2017) Effect on profit before tax (in USD ‘000) Effect on shareholders’ equity (in USD ‘000) 2017 +5 % 924 924 -5 % (924 ) (924 ) 2016 +5 % 274 274 -5 % (274 ) (274 ) GBP positions Increase /decrease exchange rate vs CHF (2016) and USD (2017) Effect on profit before tax (in USD ‘000) Effect on shareholders’ equity (in USD ‘000) 2017 +5 % 98 98 -5 % (98 ) (98 ) 2016 +5 % 193 193 -5 % (193 ) (193 ) CHF positions Increase /decrease exchange rate vs USD Effect on profit before tax (in USD ‘000) Effect on shareholders’ equity (in USD ‘000) 2017 +5 % 474 474 -5 % (474 ) (474 ) USD positions Increase /decrease exchange rate vs CHF Effect on profit before tax (in USD ‘000) Effect on shareholders’ equity (in USD ‘000) 2016 +5 % 349 349 -5 % (349 ) (349 ) Credit risk Cash and cash equivalents are deposited with top tier banks and institutions with a short term rating of “A-1” or “P-1” with Standard & Poor’s and Moody’s, respectively. The maximum credit risk exposure the Group faces in connection with its financial assets, being cash and cash equivalents and other receivables, is the carrying amounts of these balances as shown in the consolidated balance sheet. Interest rate risk The Group’s exposure to interest rate fluctuations is limited because the Group has no interest-bearing indebtedness. Liquidity risk The Group’s principal source of liquidity is the cash reserves which are obtained through the issuance of new shares. The Group’s policy is to invest these funds in low risk investments including interest bearing deposits. The ability of the Group to maintain adequate cash reserves to sustain its activities in the medium term is subject to risk as it is highly dependent on the Group’s ability to raise further funds from the sale of new shares. 3.2 Capital management The Group’s objectives when managing capital are to safeguard the Group’s ability to continue as a going concern in order to ensure the financing of successful research and development activities so that future profits can be generated and to maintain sufficient financial resources to mitigate against risks and unforeseen events. The Group is also subject to capital maintenance requirement under Swiss law. To ensure that statutory capital requirements are met, the Group monitors capital periodically. 3.3 Fair value estimation and financial instruments The carrying value less impairment provision of receivables and payables approximate their fair values due to their short-term nature. All financial assets and liabilities, respectively, are held at their amortized cost. The Group’s financial assets consist of cash and cash equivalents and other receivables which are classified as loans and receivables at amortized costs according to IAS 39. The Group’s financial liabilities consist of other payables and accruals which are classified as other liabilities at amortized cost according to IAS 39.

Cash and cash equivalents

Cash and cash equivalents	12 Months Ended
	Dec. 31, 2017
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	4. Cash and cash equivalents As at December 31, in USD ‘000 2017 2016 Bank deposits 110,841 23,292 Interest bearing deposits — 2,216 Total cash and cash equivalents as at December 31 110,841 25,508 Split by currency: 2017 2016 CHF 6 % 68 % USD 93 % 20 % EUR 1 % 10 % GBP — 2 %

Receivables and payables

Receivables and payables	12 Months Ended
	Dec. 31, 2017
Subclassifications Of Assets Liabilities And Equities [Abstract]
Receivables and payables	5. Receivables and payables As at December 31, 2017 and December 31, 2016, other receivables consist mainly of reimbursements to be received from third parties, including VAT, insurance premiums and shared-costs of research and development studies, and other payables and other current liabilities include mainly costs of clinical services. All receivables and payables are due from and to third parties and carried at amortized cost. All payables have a contract maturity within 1 year.

Prepaid expenses and deferred c

Prepaid expenses and deferred costs	12 Months Ended
	Dec. 31, 2017
Prepaid Expense And Deferred Costs [Abstract]
Prepaid expenses and deferred costs	6. Prepaid expenses and deferred costs As at December 31, 2017, prepaid expenses and deferred costs only consist of prepaid expenses. As at December 31, 2016, prepaid expenses and deferred costs include USD 2.1 million of prepayments and USD 0.3 million of costs which were incurred in connection with the Company’s Initial Public Offering (“IPO”) and related issuance of new shares. These costs, which consisted principally of legal fees, were deferred and deducted from equity upon issuance of the new shares.

Furniture, fixtures and equipme

Furniture, fixtures and equipment	12 Months Ended
	Dec. 31, 2017
Disclosure Of Property Plant And Equipment [Abstract]
Furniture, fixtures and equipment	7. Furniture, fixtures and equipment in USD ‘000 2017 2016 Net book value as at January 1 121 124 Additions 272 45 Depreciation charge (70 ) (46 ) Currency translation effects — (2 ) Net book value as at December 31 323 121 Total cost 495 223 Accumulated depreciation (172 ) (102 ) Furniture, fixtures and equipment assets mainly consist of office furniture and leasehold improvements.

Intangible assets

Intangible assets	12 Months Ended
	Dec. 31, 2017
Disclosure Of Intangible Assets [Abstract]
Intangible assets	8. Intangible assets in USD ‘000 2017 2016 Net book value as at January 1 16,608 16,857 Additions 5,000 — Amortization charge — — Currency translation effects — (249 ) Net book value as at December 31 21,608 16,608 Total cost 21,608 16,608 Accumulated amortization — — As at December 31, 2017, the Group holds a number of licenses to operate several biopharmaceutical product candidates, the value of which is recorded at USD 21.6 million (2016: USD 16.6 million). Merck Serono licenses On August 28, 2013, the Group in-licensed nolasiban for USD 4.9 million from Ares Trading S.A., an affiliate of Merck Serono (“Merck Serono”). In June 2015, the Group acquired the in-license for OBE022 from Merck Serono for an amount of USD 2.4 million. Kissei license On November 19, 2015, the Group entered into an exclusive in-license and supply agreement with Kissei Pharmaceutical Co., Ltd. (“Kissei”) to acquire the product candidate OBE2109 for which Kissei successfully completed Phase 2 trial in Japan. This in-license agreement grants the Group an exclusive license to use, develop and commercialize the product candidate worldwide excluding certain Asian countries. This in-license was acquired for an upfront cash consideration of USD 10 million, with additional contingent payments upon occurrence of certain milestones (note 19). On April 25, 2017, the Group announced the initiation of its Phase 3 clinical program for OBE2109 in uterine fibroids and related activation of sites and start of recruitment. This event triggered the recognition and payment of a USD 5.0 million milestone to Kissei during the second quarter of 2017, that was accounted for as an intangible asset. The Group has concluded that the Merck Serono licenses and the Kissei license acquisitions do not qualify as business combinations per IFRS 3, as the Group did not acquire processes that are capable of producing outputs given the in-licensed compounds are very early-stage. Amortization and impairment The licenses are currently not amortized as no regulatory and marketing approvals were obtained. In accordance with IAS 38, the licenses have been reviewed for impairment by assessing the fair value less costs of disposal (“FVLCOD”). The valuation is considered to be Level 3 in the fair value hierarchy due to unobservable inputs used in the valuation. No impairment was identified. The key assumptions used in the valuation model (income approach) to determine the FVLCOD of the licenses are as follows: • Expected research and development costs; • Probabilities of achieving development milestones based on industry standards; • Reported disease prevalence; • Expected market share; • Drug reimbursement, costs of goods and marketing expenses; and • Expected patent life. The valuation model covers a 20-year period due to the length of the development cycle for assets of this nature. A discount factor of 15%, based on the assumed cost of capital for the Group, has been used over the forecast period. Based on sensitivity analysis performed, including changes in discount rates and peak sales assumptions, no reasonably possible change in assumption would cause the carrying value of the licenses to exceed their recoverable amount.

Other long-term assets and liab

Other long-term assets and liabilities	12 Months Ended
	Dec. 31, 2017
Other Long Term Assets [Abstract]
Other long-term assets and liabilities	9. Other long-term assets and liabilities The Group’s other long-term assets mainly consist of security rental deposits for the Group’s offices. The Group’s other long-term liabilities consist of long-term components of rent costs for ObsEva USA Inc.

Post-employment benefits

Post-employment benefits	12 Months Ended
	Dec. 31, 2017
Disclosure Of Defined Benefit Plans [Abstract]
Post-employment benefits	10. Post-employment benefits In accordance with the mandatory Swiss pension fund law, all employees of the Company participate in a retirement defined benefit plan. Swiss based pension plans are governed by the Swiss Federal Law on Occupational Retirement, Survivors’ and Disability Pension Plans (the “LPP”), which stipulates that pension plans are to be managed by independent, legally autonomous units. Under the terms of the pension plan, participants are insured against the financial consequences of old age, disability and death. The various insurance benefits are governed by regulations, with the LPP specifying the minimum benefits that are to be provided. The employer and employees pay contributions to the pension plan. In the event the pension plan’s statutory funding falls below a certain level, various measures can be taken to increase funding above such level, such as increasing the current contribution, lowering the interest rate on the retirement account balances or reducing the additional prospective benefits. The employer can also make additional restructuring contributions. Since the risks of death and disability are fully reinsured by an insurance group, the savings plan must be qualified as a defined benefit plan. As required by IAS 19 Employee Benefits The investment risk is borne by the insurer and the reinsurer respectively, and the investment decision is taken by the board of trustees of the collective insurance. In 2016, the pension fund changed the pension conversion rates, what has been considered as an amendment of the pension plan. in USD ‘000 2017 2016 Change in defined benefit obligation Defined benefit obligation at January 1, (9,201 ) (7,765 ) Current service cost (795 ) (774 ) Interest cost (72 ) (70 ) Net benefits paid (1,604 ) (643 ) Currency translation effects (403 ) 163 Remeasurements: Impact of plan amendment — 512 Effect of changes in demographic assumptions — (316 ) Effect of changes in financial assumptions 155 (203 ) Effect in experience assumptions (310 ) (105 ) Defined benefit obligation at December 31, (12,230 ) (9,201 ) in USD ‘000 2017 2016 Change in plan assets Fair value of plan assets at January 1, 6,369 5,102 Interest income 55 50 Employer contributions 403 333 Employee contributions 403 333 Net benefits paid 1,604 643 Currency translation effects 284 (117 ) Remeasurements: return on plan assets (excluding interest income) 13 25 Fair value of plan assets at December 31, 9,131 6,369 Year ended December 31, in USD ‘000 2017 2016 Components of defined benefit cost Current service cost 795 774 Interest expense on defined benefit obligation 72 70 Interest income on plan assets (55 ) (50 ) Employee contributions (403 ) (333 ) Impact of plan amendment — (512 ) Total included in staff costs (note 14) 409 (51 ) Year ended December 31, in USD ‘000 2017 2016 Remeasurements recognized in other comprehensive loss Effect of changes in demographic assumptions — (316 ) Effect of changes in financial assumptions 155 (203 ) Effect in experience assumptions (310 ) (105 ) Return on plan assets (excluding interest income) 13 25 Total remeasurements recognized as other comprehensive loss (142 ) (599 ) Cumulative amount of remeasurements immediately recognized in other comprehensive loss (3,581 ) (3,439 ) As at December 31, in USD ‘000 2017 2016 Amounts recognized in the statement of financial position Defined benefit obligation (12,230 ) (9,201 ) Fair value of plan assets 9,131 6,369 Net liability (3,099 ) (2,832 ) in USD ‘000 2017 2016 Change in defined benefit liability Net defined benefit liability at January 1, (2,832 ) (2,663 ) Defined benefit cost included in statement of comprehensive loss (409 ) 51 Total remeasurements included in other comprehensive loss (142 ) (599 ) Employer contributions 403 333 Currency translation effects (119 ) 46 Net defined benefit liability at December 31, (3,099 ) (2,832 ) As of the date of preparation of these consolidated financial statements, the annual report for 2017 of the pension fund has not yet been issued, and therefore the detailed structures and assets held at December 31, 2017, are not currently available for presentation. The detailed structures and assets held at December 31, 2016, are as follows: Plan assets As at December 31, 2016 Cash 2.7 % Bonds 65.2 % Shares 9.5 % Real estate 15.1 % Mortgages 7.4 % Alternative investments 0.1 % Total 100.0 % To develop the expected long-term rate of return on asset assumption, the Group considered the current level of expected returns on risk free investments (high-quality corporate bonds), the historical level of the risk premium associated with the other asset classes in which the portfolio is invested, and the expectation for future returns of each asset allocation. The principal actuarial assumptions used were as follows: 2017 2016 Discount rate 0.80% 0.70% Salary increase (including inflation) 1.00% 1.00% Rate of pension increases 0.25% 0.25% Post-employment mortality table LPP 2015 G LPP 2015 G Sensitivity analysis illustrates the sensitivity of the Group defined benefit obligation at December 31, 2017 by varying the discount rate and the salary increase rate by plus / minus 50 basis points: in USD ‘000 Discount rate Discount rate Salary increase Salary increase Rate of pension increase Rate of pension increase Sensitivity analysis plus 50bps minus 50bps plus 50bps minus 50bps plus 25bps minus 25bps Discount rate 1.30 % 0.30 % 0.80 % 0.80 % 0.80 % 0.80 % Salary increase 1.00 % 1.00 % 1.50 % 0.50 % 1.00 % 1.00 % Rate of pension increases 0.25 % 0.25 % 0.25 % 0.25 % 0.50 % 0.00 % Defined benefit obligation (11,177 ) (13,471 ) (12,331 ) (12,135 ) (12,544 ) (11,934 ) Average duration of the defined benefit obligation 2017 2016 Duration in years 18.8 19.8 Expected contributions by the employer to be paid to the post-employment benefit plans during the annual period beginning after the end of the reporting period amount to approximately USD 440,000.

Shareholders' equity

Shareholders' equity	12 Months Ended
	Dec. 31, 2017
Disclosure Of Classes Of Share Capital [Abstract]
Shareholders' equity	11. Shareholders’ equity Number of shares in USD ‘000 Common shares Preferred A shares Preferred B shares Non- voting shares Total shares Share capital Share premium Total January 1, 2016 2,215,434 7,706,777 11,079,549 347,113 21,348,873 1,694 99,597 101,291 Issuance of preferred A shares — 325,000 — — 325,000 26 2,366 2,392 Share issuance costs — — — — — — (33 ) (33 ) Issuance of non-voting shares to employees — — — 264,524 264,524 20 675 695 Offset of accumulated losses with share premium — — — — — — (30,639 ) (30,639 ) December 31, 2016 2,215,434 8,031,777 11,079,549 611,637 21,938,397 1,740 71,966 73,706 Number of shares in USD ‘000 Common shares Preferred A shares Preferred B shares Non- voting shares Total shares Share capital Share premium Total January 1, 2017 2,215,434 8,031,777 11,079,549 611,637 21,938,397 1,740 71,966 73,706 Conversion of preferred and non-voting shares 19,722,963 (8,031,777 ) (11,079,549 ) (611,637 ) — — — — Issuance of shares - IPO 6,450,000 — — — 6,450,000 496 96,254 96,750 Issuance of shares - PIPE 7,500,000 — — — 7,500,000 592 59,408 60,000 Issuance 454,548 — — — 454,548 36 3,671 3,707 Share issuance costs — — — — — — (11,964 ) (11,964 ) December 31, 2017 36,342,945 — — — 36,342,945 2,864 219,335 222,199 Share capital and share premium As at December 31, 2017, the total outstanding share capital of USD 2.9 million, fully paid, consisted of 36,342,945 common shares, excluding 778,134 non-vested shares and 10,183 treasury shares. As at December 31, 2016, the total outstanding share capital of USD 1.7 million consisted of 2,215,434 common shares, 8,031,777 series A preferred shares, 11,079,549 series B preferred shares and 611,637 non-voting shares, excluding 1,237,665 non-vested non-voting shares and 5,200 treasury non-voting shares. Series A preferred shares and series B preferred shares had preferential rights as to the liquidation proceeds within the terms of the article of association, and conferred the same voting rights as those attached to common shares. Non-voting shares were part of the non-voting share capital and had the same financial rights than those attached to common shares, with no right to vote or to participate in the ordinary and extraordinary meetings of the Group. The Company’s non-voting shares and series A and series B preferred shares were converted into common shares upon the closing of the IPO. All shares have a nominal value of 1/13 of a Swiss franc, translated into USD using historical rates at the issuance date. On February 23, 2016, the shareholders approved for statutory purposes a resolution to offset the accumulated losses with the share premium balance for an amount of USD 30.6 million. This transaction had no impact on the overall equity position. In August 2016, the Group’s product candidate known as OBE022 entered into a Phase 1 clinical trial, triggering the obligation of payment to Merck Serono of the 325,000 series A preferred shares due upon occurrence of that event. The 325,000 shares were issued through a capital increase of the Group on September 28, 2016, and an amount of USD 2.4 million was reclassified from the share-based payment reserve to the share premium. On January 30, 2017, the Company completed an IPO and issued 6,450,000 common shares at a subscription price of USD 15.00 per share and a par value of 1/13 of a Swiss franc per share. The gross proceeds of USD 96.8 million have been recorded in equity net of directly related share issuance costs of USD 8.2 million. On October 13, 2017, the Company completed a private placement with institutional investors and issued 7,500,000 common shares at a subscription price of USD 8.00 per share and a par value of 1/13 of a Swiss franc per share. The gross proceeds of USD 60.0 million have been recorded in equity net of directly related share issuance costs of USD 3.7 million. Equity incentive plans In 2017, the Company issued 454,548 common shares (2016: 264,524 non-voting shares) under its 2013 EIP (see note 18). All shares and non-voting shares issued under the 2013 EIP have a nominal value of 1/13 of a Swiss franc, translated into USD using historical rates at the issuance date. Authorized share capital The authorized share capital that is not outstanding as at December 31, 2017 and December 31, 2016 is as follows: As at December 31, Number of shares 2017 2016 Authorized share capital 6 11,590,631 On January 26, 2018, the authorized share capital of the Company has been increased to 18,565,625 shares by resolution of an Extraordinary General Meeting of the Shareholders.

Revenue and other income

Revenue and other income	12 Months Ended
	Dec. 31, 2017
Disclosure Of Revenue And Other Income Abstract
Revenue and other income	12. Revenue and other operating income The Group currently derives no revenue from sales of its biopharmaceutical product candidates. Operating income other than revenue mainly relates to compensation received from the Swiss tax authorities as the Company acts as collecting agent of the withholding tax on salaries.

Operating expenses by nature

Operating expenses by nature	12 Months Ended
	Dec. 31, 2017
Expense By Nature [Abstract]
Operating expenses by nature	13. Operating expenses by nature Year ended December 31, in USD ‘000 2017 2016 2015 External research and development costs 43,268 16,811 10,784 Staff costs (note 14) 17,999 7,436 7,313 Professional fees 2,862 4,016 743 Rents 592 427 367 Travel expenses 1,073 541 313 Patent registration costs 426 512 87 Depreciation 70 46 36 Other 1,190 374 203 Total operating expenses by nature 67,480 30,163 19,846 Due to the difficulty in assessing when research and development projects would generate revenue, the Group expenses all research and development costs on the consolidated statement of comprehensive loss. In 2017, research and development expenses amounted to USD 54.9 million (2016: USD 23.7 million, 2015: USD 16.9 million). The depreciation expense has been allocated as follows: Year ended December 31, in USD ‘000 2017 2016 2015 Research and development expenses 44 35 28 General and administrative expenses 26 11 8 Total depreciation 70 46 36

Staff costs

Staff costs	12 Months Ended
	Dec. 31, 2017
Disclosure Of Staffing Costs [Abstract]
Staffing costs	14. Staff costs Year ended December 31, in USD ‘000 2017 2016 2015 Wages and salaries 7,715 4,807 3,384 Social charges 993 443 337 Post-employment benefits expense 435 (51 ) 324 Share-based payments 8,856 2,237 3,268 Total staff costs 17,999 7,436 7,313 The Group employed on average 32.3 full-time equivalents (“FTE”) in 2017, compared to 22.4 FTE in 2016 and 16.2 FTE in 2015, and 37.7 FTE as at December 31, 2017 compared to 25.3 FTE as at December 31, 2016 and 19.9 FTE as at December 31, 2015. For the year ended December 31, 2016, the post-employment benefits line includes a gain of USD 512 thousand relating to the plan amendment enacted in 2016.

Finance income and expense

Finance income and expense	12 Months Ended
	Dec. 31, 2017
Analysis Of Income And Expense [Abstract]
Finance income and expense	15. Finance income and expense Finance income mainly relates to foreign exchange gains and interests on bank deposits. Finance expense mainly relates to foreign exchange losses and interest expense.

Income taxes and deferred taxes

Income taxes and deferred taxes	12 Months Ended
	Dec. 31, 2017
Disclosure Of Income Tax [Abstract]
Income taxes and deferred taxes	16. Income taxes and deferred taxes The Group is subject to income taxes in Switzerland, Ireland and the United States. The Company is subject in Switzerland to a municipal and cantonal income tax rate of 22.6% and to a federal tax rate of 8.5% on its profits after tax. It is entitled to carry forward any loss incurred for a period of seven years and can offset such losses carried forward against future taxes. In 2015, the Company was granted by the State Council of the Canton of Geneva an exemption of income and capital tax at municipal and cantonal levels for the period from 2013 until 2022. Because of this exemption, and the fact that the Company has incurred net losses since its inception, no income tax expense at the municipal, cantonal or federal levels was recorded in the Company for the years ended December 31, 2017 and 2016. Additionally, due to the uncertainty as to whether it will be able to use its net loss carryforwards for tax purposes in the future, no deferred taxes have been recognized on the balance sheet of the Company as of December 31, 2017 and December 31, 2016. The following details the tax losses carry forwards of the Company and their respective expiring dates. Expiring tax losses As at December 31, in USD ‘000 2017 2016 2020 2,925 2,808 2021 11,587 11,123 2022 16,253 15,602 2023 28,631 27,484 2024 58,596 — Total unrecorded tax losses carry forwards 117,992 57,017 The Company’s Irish subsidiary has no activity, and, therefore, no income tax expense was recorded in such entity for the years ended December 31, 2017 and 2016. The Company’s U.S. subsidiary, ObsEva USA Inc., is a service organization for the Group and is therefore subject to taxes on the revenues generated from its services to the Group that are charged based upon the U.S. subsidiary’s cost plus arrangement with the Group. Because the U.S. subsidiary started operating in January 2017, no income tax expense was recorded in such entity for the year ended December 31, 2016. The profits of the U.S. subsidiary for the year ended December 31, 2017 were subject to a total U.S. income tax rate of 39.3% based on both the U.S. federal and Massachusetts state tax rates. The income tax for the year ended December 31, 2017 was USD 51 thousand. Additionally, due to the uncertainty as to whether ObsEva USA Inc. will be able to use a deferred tax asset for tax purposes in the future, no deferred taxes have been recognized on the balance sheet of the Group as of December 31, 2017 and December 31, 2016. The following elements explain the difference between the income tax expense at the applicable Group tax rate and the effective income tax expense: Year ended December 31, 2017 in USD ‘000 ObsEva SA ObsEva USA Total Group Net loss before tax (65,397 ) (1,478 ) (66,875 ) Statutory tax rate (blended at Group level) 7.8 % 39.3 % 8.5 % Income tax credit at statutory tax rates (5,123 ) (581 ) (5,704 ) Tax impact of permanent differences 577 225 802 Temporary differences not recognized as deferred tax assets — 407 407 Tax on losses not recognized as deferred tax assets 4,546 — 4,546 Effective income tax expense — 51 51 Effective tax rate 0 % 3.5 % 0.1 % Year ended December 31, 2016 in USD ‘000 ObsEva SA ObsEva USA Total Group Net loss before tax (30,202 ) — (30,202 ) Statutory tax rate (blended at Group level) 7.8 % — 7.8 % Income tax credit at statutory tax rates (2,366 ) — (2,366 ) Tax impact of permanent differences 145 — 145 Tax on losses not recognized as deferred tax assets 2,221 — 2,221 Effective income tax expense — — — Effective tax rate 0 % 0 %

Loss per share

Loss per share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Loss per share	17. Loss per share As of December 31, 2017, the Company has one category of shares, which are common shares. As of December 31, 2016 and 2015, the Company’s shares were comprised of ordinary shares, consisting of both common shares and non-voting shares, and series A and series B preferred shares. The Company’s non-voting shares and series A and series B preferred shares were converted into common shares upon the closing of the IPO on January 25, 2017. For the years ended December 31, 2016 and 2015, as the series A and series B preferred shares participated with ordinary shares in the profit or loss on a pro-rata basis, the net loss was allocated to each class pro-rata to their weighted average number of shares outstanding during the period. The basic loss per share is calculated by dividing the loss of the period attributable to the ordinary shares by the weighted average number of ordinary shares (common and non-voting) outstanding during the period as follows: Year ended December 31, 2017 Common shares Net loss attributable to shareholders(in USD ‘000) (66,926) Weighted average number of shares outstanding 29,799,047 Basic and diluted loss per share (in USD) (2.25) Year ended December 31, 2016 Preferred B shares Preferred A shares Common and non-voting shares Net loss attributable to shareholders (in USD ‘000) (15,516 ) (10,910 ) (3,776 ) Weighted average number of shares outstanding 11,079,549 7,790,475 2,695,898 Basic and diluted loss per share (in USD) (1.40 ) (1.40 ) (1.40 ) Year ended December 31, 2015 Preferred B shares Preferred A shares Common and non-voting shares Net loss attributable to shareholders (in USD ‘000) (2,380 ) (14,384 ) (3,102 ) Weighted average number of shares outstanding 1,274,910 7,706,777 1,661,231 Basic and diluted loss per share (in USD) (1.87 ) (1.87 ) (1.87 ) For the year ended December 31, 2017, 778,134 non-vested shares, 10,183 treasury shares and 1,866,740 shares issuable upon the exercise of stock-options, which would have an anti-dilutive impact on the calculation of the diluted earnings per share, were excluded from the calculation. For the year ended December 31, 2016, 1,237,662 non-vested shares, 5,200 treasury shares and no shares issuable upon the exercise of stock-options were excluded. For the year ended December 31, 2015, 623,145 non-vested shares, 80,353 treasury shares and no shares issuable upon the exercise of stock-options were excluded.

Share-based compensation

Share-based compensation	12 Months Ended
	Dec. 31, 2017
Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Abstract]
Share-based compensation	18. Share-based compensation The total expenses arising from share-based payment transactions recognized during the period as part of staff costs were as follows: Year ended December 31, in USD ‘000 2017 2016 2015 Employee 2013 EIP 5,497 2,237 890 Employee 2017 EIP 3,359 — — Anti-dilution provisions — — 2,378 Total share-based compensation 8,856 2,237 3,268 Employee equity incentive plan 2013 The Company established the 2013 EIP for employees, executives, directors and consultants (the “Beneficiaries”) of the Group . Upon enrollment in the 2013 EIP, Beneficiaries were granted a certain number of shares which they were entitled to acquire at a pre-determined price of 1/13 of a Swiss franc. The pre-determined price was generally paid by the Beneficiaries at the grant date and recognized as a pre-payment until the vesting period elapses resulting in the shares issuance being accounted for. The shares generally fully vest over a four year vesting period, with 25% of the shares underlying the grant vesting after one year, and 1/48 th The Group has no present obligation to repurchase or settle the shares in cash. 2017 2016 2015 Number of shares issued under the 2013 EIP 454,548 264,524 182,429 Average grant date fair value (in USD) — 11.37 2.48 Expense arising from the 2013 EIP (in USD ’000) 5,497 2,237 890 The fair value of the shares was calculated using a combination of the discounted cash flow method, under the income approach, and the backsolve method. The income approach estimates value based on the expectation of future cash flows that the Company will generate, such as cash earnings, costs savings, tax deduction and the proceeds from disposition. These future cash flows were discounted to their present values using a discount rate derived based on an analysis of the cost of capital of comparable publicly traded companies in similar lines of business, as of each valuation date, and was adjusted to reflect the risks inherent in the Company’s cash flows. The backsolve method, a form of the market approach to valuation, derives the implied enterprise equity value and the fair value of the non-voting share from a recent and contemporaneous transaction involving the Company’s own securities, using the following assumptions: rights and preferences of the different categories of shares, probability of various liquidity event scenarios, expected timing of a liquidity event, volatility and expected value in a liquidity event. The Group has stopped granting equity instruments under the 2013 EIP in 2016. Employee equity incentive plan 2017 The Company established in 2017 the 2017 EIP for Beneficiaries of the Group, under which 1,866,740 stock-options were granted during the year ended December 31, 2017. The stock-options vest under a 3-year or 4-year vesting schedule, have a 10-year expiration term and have a strike price equivalent to the share price at grant date. Movements in the number of stock-options outstanding under the 2017 EIP were as follows: 2017 At January 1, — Granted 1,866,740 Forfeited — Exercised — At December 31, 1,866,740 At December 31, 2017, of the outstanding 1,866,740 stock-options, 46,708 were exercisable. The outstanding stock-options have the following range of exercise prices and expiration dates: Range of exercise prices Expiration date 2020 USD 15.00 to USD 17.99 136,500 USD 12.00 to USD 14.99 31,950 USD 9.00 to USD 11.99 1,173,290 USD 6.00 to USD 8.99 525,000 Total outstanding options 1,866,740 The weighted average fair value of the stock-options granted during the year ended December 31, 2017, determined using a Black-Scholes model was USD 6.98. The significant inputs to the model were: 2017 Weighted average share price at grant date USD 9.19 Weighted average strike price USD 9.19 Weighted average 10-year volatility 58 % Dividend yield 0 % Weighted average 10-year risk free rate 2.35 % Since the Company has a short track record as a public company, expected volatility has been determined based on the historical trend of an appropriate sample of public companies operating in the biotech and pharmaceutical industry. Anti-dilution provisions The shareholders’ agreement signed in 2013 included specific anti-dilution clauses benefiting one of the Group’s founders, Ernest Loumaye (the “Founder”). Subject to specified exceptions, per this clause, if, as a result of a share issuance, the Founder’s shareholding in the Group’s certain classes of shares was diluted below 10%, then the Founder was entitled to acquire at nominal value (1/13 of a Swiss franc) a number of common shares allowing him to maintain his shareholding at 10%. In November 2015, the completion of a round of financing (note 11) triggered this clause which resulted in the issuance of 915,434 common shares to the Founder. In accordance with IFRS 2, such transaction resulted in a share-based expense of USD 2.4 million for the year ended December 31, 2015. The fair value of the common shares delivered to the Founder was calculated using a backsolve method (USD 2.68). The anti-dilution provisions are no longer effective and had no impact on the years ended December 31, 2017 and 2016.

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Dec. 31, 2017
Disclosure Of Commitments And Contingencies [Abstract]
Commitments and contingencies	19. Commitments and contingencies Operating lease commitments As at December 31, in USD ‘000 2017 2016 Within 1 year 535 243 Later than 1 year and no later than 5 years 2,145 121 Later than 5 years 144 — Total 2,824 364 Operating lease commitments relate to the Group’s lease for its headquarters in Geneva, Switzerland and its subsidiary’s lease in Boston, Massachusetts, USA. Contingencies As a result of the licenses granted to the Group, the following contingencies are to be noted: Kissei license Under the terms of the license and supply agreement, the Group would be obligated to make milestone payments upon the achievement of specified regulatory milestones with respect to OBE2109. The total of all potential undiscounted future payments that the Group could be required to make under this arrangement ranges between USD 0 and USD 188 million, of which USD 5 million have already been paid. Pursuant to the Kissei license and supply agreement, the Group has agreed to exclusively purchase the active pharmaceutical ingredient for OBE2109 from Kissei. During the development stage, the Group is obligated to pay Kissei a specified supply price. Following the first commercial sale of licensed product, the Group is obligated to pay Kissei a royalty payment in the low twenty percent range as a percentage of net sales, which includes payment for Kissei’s supply of the active pharmaceutical ingredient until the latest of the date that the valid claim of a patent for the product has expired, the expiration of our regulatory exclusivity period or 15 years from the first commercial sale of such product on a country-by-country and product-by-product basis. Merck Serono licenses Under the terms of the two license agreements with Merck Serono for nolasiban and OBE022, the Group would be obligated to pay Merck Serono a high-single digit and a mid-single digit royalty, respectively, of net sales generated by the Group, its affiliates or sub-licensees of any product containing the in-licensed compounds.

Related parties transactions

Related parties transactions	12 Months Ended
	Dec. 31, 2017
Disclosure Of Transactions Between Related Parties [Abstract]
Related parties transactions	20. Related parties transactions As of December 31, 2017, the Group’s related parties include key management (Board of Directors and Executive Committee) and members of their immediate families. The following transactions were carried out with related party: • Key management remuneration The Board of Directors is composed of 8 members, whereas the Executive Committee is composed of 6 members. The following table sets forth the total remuneration recorded for members of the Board of Directors and Executive Committee: Year ended December 31, in USD ‘000 2017 2016 Short-term employee benefits (including base and variable cash remuneration) 3,403 1,890 Post-employment benefits 135 (18 ) Share-based payments 6,451 1,614 Total 9,989 3,486 • Other transactions with related parties There were no other significant transactions with related parties during the years presented.

Going concern

Going concern	12 Months Ended
	Dec. 31, 2017
Disclosure Of Going Concern [Abstract]
Going concern	21. Going concern The Group fulfills its obligations by the use of its cash reserves. The Board of Directors believes the Group will be able to meet all of its obligations for a further 12 months as they fall due and, hence, the consolidated financial statements have been prepared on a going concern basis.

Events after the reporting peri

Events after the reporting period	12 Months Ended
	Dec. 31, 2017
Disclosure Of Nonadjusting Events After Reporting Period [Abstract]
Events after the reporting period	22. Events after the reporting period There were no material events after the balance sheet date.

Accounting principles applied28

Accounting principles applied in the preparation of the consolidated financial statements (Policies)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Accounting Policy [Abstract]
Basis of preparation	2.1 Basis of preparation These consolidated financial statements have been prepared in accordance with the International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). The consolidated financial statements are based on a historical cost basis. The preparation of financial statements in conformity with IFRS requires the use of certain critical accounting estimates. It also requires management to exercise its judgement in the process of applying the Group’s accounting policies. The areas involving a higher degree of judgement or complexity, or areas where assumptions and estimates are significant to the consolidated financial statements, are disclosed in note 2.5. Due to rounding, numbers presented throughout these consolidated financial statements may not add up precisely to the totals provided. All ratios and variances are calculated using the underlying amount rather than the presented rounded amount.
Scope of consolidation	2.2 Scope of consolidation Subsidiaries are all entities over which the Group has control. The Group controls an entity when the Group is exposed to, or has rights to, variable returns from its involvement with the entity and has the ability to affect those returns through its power to direct the activities of the entity. Subsidiaries are fully consolidated from the date on which control is transferred to the Group. They are deconsolidated from the date that control ceases. The Company currently consolidates the financial operations of its two fully-owned subsidiaries, ObsEva Ireland Ltd, which is registered in Cork, Ireland and organized under the laws of Ireland, and ObsEva USA Inc., which is registered and organized under the laws of Delaware, USA. ObsEva Ireland Ltd had no operations and no results of operations to report as of December 31, 2017 and 2016. ObsEva USA Inc. had no operations and no results of operations to report as of December 31, 2016.
Standards and interpretations published by the IASB	2.3 Standards and interpretations published by the IASB The IASB and the International Financing Reporting Standards Interpretations Committee have recently issued new standards and interpretations to be applied to the Group’s consolidated financial statements. No new standards and amendments applied by the Group in 2017 had an impact on its consolidated financial statements. In 2018, the Group will adopt the following new relevant standards: IFRS 9 Financial Instruments, effective on January 1, 2018, with early adoption allowed In July 2014, the IASB issued IFRS 9 Financial Instruments Financial Instruments: Recognition and Measurement IFRS 15 Revenue from Contracts with Customers, effective on January 1, 2018, with early adoption allowed In May 2014, the IASB issued IFRS 15 Revenue from Contracts with Customers Construction Contracts Revenue In 2019, the Group expects to adopt the following new relevant standards: IFRS 16 Leases, effective for annual periods beginning on or after January 1, 2019 In January 2016, the IASB issued IFRS 16 Leases Leases Other new standards and amendments published but not yet effective will have no material impact on the consolidated financial statements of the Group.
Current assets	Current assets Other receivables and other current receivables or prepayments are carried at their nominal value. Individual receivables that are known to be uncollectible are written off by reducing the carrying amount directly. The Group considers that there is evidence of impairment if any of the following indicators are present: • significant financial difficulties of the debtor; • probability that the debtor will enter bankruptcy or financial reorganization; and • default or delinquency in payments (more than 30 days overdue). Receivables for which an impairment provision was recognized are written off against the provision when there is no expectation of recovering additional cash.
Plant and Equipment	Furniture, fixtures and equipment Furniture, fixtures and equipment are carried at cost less depreciation and impairment. Historical cost includes expenditure that is directly attributable to the acquisition of the items. Depreciation is calculated using the straight-line method, on the basis of the following useful lives: • furniture 5 years • hardware 3 years • leasehold improvement duration of lease Furniture, fixtures and equipment are reviewed for impairment whenever events or changes in circumstances indicate that their carrying amount may not be recoverable, on an individual basis. An impairment loss is recognized for the amount by which the asset’s carrying amount exceeds its recoverable amount. The assets’ residual values and useful lives are reviewed, and adjusted if appropriate, at the end of each reporting period.
Intangible assets	Intangible assets Separately acquired patents, licenses and other intangible assets are recorded at historical cost and subsequently measured at cost less accumulated amortization and any impairment losses. The acquisition of certain intangible assets, mainly licenses, may involve additional payments contingent on the occurrence of specific events or milestones. Unless the Group already has a present obligation to make the payment at a future date, the initial measurement of the intangible asset does not include such contingent payments. Instead, such payments are subsequently capitalized as intangible assets when the contingency or milestone occurs. Estimated useful life is the lower of legal duration and economic useful life, which does not exceed 20 years. The estimated useful life of the intangible assets is annually reviewed, and if necessary, the future amortization charge is accelerated. For licenses, the amortization starts when the assets become available for use, generally once proper regulatory and marketing approval are obtained. Intangible assets are subject to impairment testing annually, and whenever events or changes in circumstances indicate that the carrying amount may not be recoverable.
Post-employment benefits	Post-employment benefits Group companies operate various pension schemes. All employees of ObsEva SA participate in a retirement defined benefit plan. A defined benefit plan is a pension plan that defines an amount of pension benefit that an employee will receive on retirement, usually dependent on one or more factors such as age, years of service and compensation. The liability recognized in the balance sheet in respect of defined benefit pension plans is the present value of the defined benefit obligation at the end of the reporting period less the fair value of plan assets. The defined benefit obligation is calculated annually by an independent actuary, using the projected unit credit method. The present value of the defined benefit obligation is determined by discounting the estimated future cash outflows using interest rates of high-quality corporate bonds that are denominated in the currency in which the benefits will be paid, and that have terms to maturity approximating to the terms of the related pension obligation. Actuarial gains and losses arising from experience adjustments and changes in actuarial assumptions are charged or credited to equity in other comprehensive income in the period in which they arise. Past-service costs are recognized immediately in the consolidated statement of comprehensive loss. During 2017, ObsEva USA, Inc established a 401K, defined contribution plan, for the employees of the company. A defined contribution plan is a pension plan under which the amounts paid by the employer are fixed in advance. The plan assets are held by a third party custodian. ObsEva USA, Inc. contributions to the defined contribution plan are charged to the income statement as incurred. The Group has no further obligation once the contributions have been paid.
Equity	Equity Incremental costs directly attributable to the issuance of common shares and options are recognized as a deduction from equity, net of any tax effects.
Research and development	Research and development Research expenses are charged to the consolidated statement of comprehensive loss as incurred. Development expenses are capitalized as intangible assets when it is probable that future economic benefits will flow to the Group, and the following criteria are fulfilled: • it is technically feasible to complete the intangible asset so that it will be available for use or sale; • management intends to complete the intangible asset and use or sell it; • there is an ability to use or sell the intangible asset; • adequate technical, financial and other resources to complete the development and to use or sell the intangible asset are available; and • the expenditure attributable to the intangible asset during its development can be reliably measured. In the opinion of management, due to uncertainties inherent in the development of the Group’s product candidates, the criteria for development costs to be recognized as an asset as defined by IAS 38 Intangible Assets
Foreign currencies	Foreign currencies Functional and presentation currency Items included in the consolidated financial statements of the Group are measured using the currency of the primary economic environment in which each Group’s entity operates (the “functional currencies”). Until December 31, 2016, the functional currency of the Company was the Swiss franc (CHF). As from January 1, 2017, due to a change of its primary economic environment, the functional currency of ObsEva SA became the US dollar (USD), which is also the functional currency of ObsEva USA, Inc. and the presentation currency of the Group. Transactions and balances Foreign currency transactions are translated into the functional currency using the exchange rates at the dates of the transactions or valuation where items are re-measured. Foreign exchange gains and losses resulting from the settlement of such transactions and from the translation of monetary assets and liabilities denominated in foreign currencies at year end exchange rates are recognized in profit or loss. Foreign exchange gains and losses that relate to borrowings are presented in the consolidated statement of comprehensive loss, within finance costs. All other foreign exchange gains and losses are presented in the consolidated statement of comprehensive loss on a net basis within other income or other expenses. Translation into the presentation currency until December 31, 2016 The results and financial position of operations that had a functional currency different from the presentation currency were translated into the presentation currency as follows: • assets and liabilities were translated at the exchange rate prevailing on December 31 of each year; • income and expenses were translated at average exchange rates; and • all resulting exchange differences were recognized in other comprehensive income. The following rates have been used for the translation from the functional currency to the presentation currency: Income statement Balance sheet Average rate (CHF) Closing rate as of December 31, (CHF) 2016 2015 2016 2015 USD 0.9850 0.9624 1.0160 1.0010
Share-based compensation	Share-based compensation The Group operates two equity incentive plans. A share-based, equity-settled, plan was formally set-up by the Group in 2013 (the “2013 EIP”). Participants eligible for awards under the 2013 EIP are executives, directors, employees, agents and consultants. The fair value of the shares granted under the 2013 EIP is determined at each grant date by using either an option pricing method that uses a Black-Scholes model or a hybrid method, as appropriate, both based on a combination of the discounted cash flow method, under the income approach, and the backsolve method. A share-based, equity-settled, plan was formally set-up by the Group in 2017 (the “2017 EIP”). Participants eligible for awards under this plan are executives, directors, employees, agents and consultants. The fair value of the stock-options granted under the 2017 EIP is determined at each grant date by using a Black-Scholes model. When the equity instruments granted do not vest until the counterparty completes a specified period of services, the Group accounts for those services as they are rendered by the counterparty, during the vesting period, with a corresponding increase in equity.
Deferred income taxes	Deferred income taxes Deferred income tax is provided in full, using the liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the consolidated financial statements. However, if the deferred income tax arises from initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit and loss, it is not accounted for. Deferred income tax is determined using tax rates and laws that have been enacted or substantively enacted by the balance sheet date and are expected to apply when the related deferred income tax asset is realized or the deferred income tax liability is settled. Deferred income tax assets are recognized to the extent that it is probable that future taxable profit will be available against which the temporary differences can be utilized.
Leases	Leases Leases of assets under which all the risks and rewards of ownership are effectively retained by the lessor are classified as operating leases, and payments made are charged to the statement of comprehensive loss on a straight-line basis.
Segment information	Segment information The Group operates in one segment, which is the research, development of innovative women’s reproductive, health and pregnancy therapeutics. The marketing and commercialization of such therapeutics depend, in large part, on the success of the development phase. The Chief Executive Officer of the Company reviews the consolidated statement of operations of the Group on an aggregated basis and manages the operations of the Group as a single operating segment. The Group currently generates no revenue from the sales of therapeutics products. The Group’s activities are not affected by any significant seasonal effect. The geographical analysis of non-current assets is as follows: As at December 31, in USD ‘000 2017 2016 Switzerland 21,832 16,819 USA 289 — Total non-current assets as at December 31 22,121 16,819 The geographical analysis of operating expenses is as follows: Year ended December 31, in USD ‘000 2017 2016 2015 Switzerland 63,956 30,163 19,846 USA 3,524 — — Total operating expenses 67,480 30,163 19,846
Critical accounting estimates and judgments	2.5 Critical accounting estimates and judgments Estimates and judgments are continually evaluated and are based on historical experience and other factors, including expectations of future events that are believed to be reasonable under the circumstances. Critical accounting estimates and assumptions The Group makes estimates and assumptions concerning the future. The resulting accounting estimates will not necessarily equal to related actual outcome. The following areas involve a higher degree of judgement or complexity or are areas where assumptions and estimates can have a significant impact on the consolidated financial statements: • Post-employment obligations: the actuarial valuation involves making assumptions about discount rates, future salary increases, mortality rates and future pension increases. Due to the long-term nature of these plans, such estimates are subject to significant uncertainty (note 10); • Share-based compensation: the determination of the fair value of the equity instruments granted involves the use of certain assumptions subject to judgement (note 18); • Commencement of depreciation and amortization: the depreciation and amortization starts when the assets are available for use in the manner intended by management, which requires judgement (notes 7 and 8); • Research and development costs: the Group recognizes expenditure incurred in carrying out its research and development activities until it becomes probable that future economic benefits will flow to the Group, which results in recognizing such costs as intangible assets, involving a certain degree of judgement (note 13); • Deferred taxes: the recognition of deferred tax assets requires assessment of whether it is probable that sufficient future taxable profit will be available against which the deferred tax assets can be utilized (note 16); • Impairment of assets: as part of impairment tests, the recoverable amounts of tested assets have been determined based on fair value calculations requiring the use of certain assumptions, subject to judgement (note 8); • Changes in functional currency: the determination of the functional currencies of Group’s companies based on the primary economic environment of each entity requires a certain degree of judgement from management.

Accounting principles applied29

Accounting principles applied in the preparation of the consolidated financial statements (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Accounting Policy [Abstract]
Summary of Useful Lives of Furniture Fixtures and Equipment	Furniture, fixtures and equipment are carried at cost less depreciation and impairment. Historical cost includes expenditure that is directly attributable to the acquisition of the items. Depreciation is calculated using the straight-line method, on the basis of the following useful lives: • furniture 5 years • hardware 3 years • leasehold improvement duration of lease
Schedule of Rates Used for Translation from Functional Currency to Presentation Currency	The following rates have been used for the translation from the functional currency to the presentation currency: Income statement Balance sheet Average rate (CHF) Closing rate as of December 31, (CHF) 2016 2015 2016 2015 USD 0.9850 0.9624 1.0160 1.0010
Summary of Geographical Analysis of Assets	The geographical analysis of non-current assets is as follows: As at December 31, in USD ‘000 2017 2016 Switzerland 21,832 16,819 USA 289 — Total non-current assets as at December 31 22,121 16,819
Summary of Geographical Analysis of Operating Expenses	The geographical analysis of operating expenses is as follows: Year ended December 31, in USD ‘000 2017 2016 2015 Switzerland 63,956 30,163 19,846 USA 3,524 — — Total operating expenses 67,480 30,163 19,846

Financial risk management (Tabl

Financial risk management (Tables)	12 Months Ended
	Dec. 31, 2017
Financial Risks Management [Abstract]
Schedule of Sensitivity of Profit or Loss to Changes in Exchange Rates	The sensitivity of profit or loss to changes in the exchange rates in the reported periods are as follows: EUR positions Increase /decrease exchange rate vs CHF (2016) and USD (2017) Effect on profit before tax (in USD ‘000) Effect on shareholders’ equity (in USD ‘000) 2017 +5 % 924 924 -5 % (924 ) (924 ) 2016 +5 % 274 274 -5 % (274 ) (274 ) GBP positions Increase /decrease exchange rate vs CHF (2016) and USD (2017) Effect on profit before tax (in USD ‘000) Effect on shareholders’ equity (in USD ‘000) 2017 +5 % 98 98 -5 % (98 ) (98 ) 2016 +5 % 193 193 -5 % (193 ) (193 ) CHF positions Increase /decrease exchange rate vs USD Effect on profit before tax (in USD ‘000) Effect on shareholders’ equity (in USD ‘000) 2017 +5 % 474 474 -5 % (474 ) (474 ) USD positions Increase /decrease exchange rate vs CHF Effect on profit before tax (in USD ‘000) Effect on shareholders’ equity (in USD ‘000) 2016 +5 % 349 349 -5 % (349 ) (349 )

Cash and cash equivalents (Tabl

Cash and cash equivalents (Tables)	12 Months Ended
	Dec. 31, 2017
Cash And Cash Equivalents [Abstract]
Schedule of Cash and Cash Equivalents	As at December 31, in USD ‘000 2017 2016 Bank deposits 110,841 23,292 Interest bearing deposits — 2,216 Total cash and cash equivalents as at December 31 110,841 25,508
Schedule of Percentage of Bank Held Cash and Cash Equivalents Split by Currency	Split by currency: 2017 2016 CHF 6 % 68 % USD 93 % 20 % EUR 1 % 10 % GBP — 2 %

Furniture, fixtures and equip32

Furniture, fixtures and equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Property Plant And Equipment [Abstract]
Schedule of Furniture, Fixtures and Equipment	in USD ‘000 2017 2016 Net book value as at January 1 121 124 Additions 272 45 Depreciation charge (70 ) (46 ) Currency translation effects — (2 ) Net book value as at December 31 323 121 Total cost 495 223 Accumulated depreciation (172 ) (102 )

Intangible assets (Tables)

Intangible assets (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Intangible Assets [Abstract]
Schedule of Detailed Information of Intangible Assets	in USD ‘000 2017 2016 Net book value as at January 1 16,608 16,857 Additions 5,000 — Amortization charge — — Currency translation effects — (249 ) Net book value as at December 31 21,608 16,608 Total cost 21,608 16,608 Accumulated amortization — —

Post-employment benefits (Table

Post-employment benefits (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Defined Benefit Plans [Abstract]
Schedule of Defined Benefit Plans	In 2016, the pension fund changed the pension conversion rates, what has been considered as an amendment of the pension plan. in USD ‘000 2017 2016 Change in defined benefit obligation Defined benefit obligation at January 1, (9,201 ) (7,765 ) Current service cost (795 ) (774 ) Interest cost (72 ) (70 ) Net benefits paid (1,604 ) (643 ) Currency translation effects (403 ) 163 Remeasurements: Impact of plan amendment — 512 Effect of changes in demographic assumptions — (316 ) Effect of changes in financial assumptions 155 (203 ) Effect in experience assumptions (310 ) (105 ) Defined benefit obligation at December 31, (12,230 ) (9,201 )
Schedule of Fair Value of Plan Assets	in USD ‘000 2017 2016 Change in plan assets Fair value of plan assets at January 1, 6,369 5,102 Interest income 55 50 Employer contributions 403 333 Employee contributions 403 333 Net benefits paid 1,604 643 Currency translation effects 284 (117 ) Remeasurements: return on plan assets (excluding interest income) 13 25 Fair value of plan assets at December 31, 9,131 6,369
Summary of Components of Defined Benefit Cost	Year ended December 31, in USD ‘000 2017 2016 Components of defined benefit cost Current service cost 795 774 Interest expense on defined benefit obligation 72 70 Interest income on plan assets (55 ) (50 ) Employee contributions (403 ) (333 ) Impact of plan amendment — (512 ) Total included in staff costs (note 14) 409 (51 )
Summary of Remeasurement Components Recognized in Other Comprehensive Loss	Year ended December 31, in USD ‘000 2017 2016 Remeasurements recognized in other comprehensive loss Effect of changes in demographic assumptions — (316 ) Effect of changes in financial assumptions 155 (203 ) Effect in experience assumptions (310 ) (105 ) Return on plan assets (excluding interest income) 13 25 Total remeasurements recognized as other comprehensive loss (142 ) (599 ) Cumulative amount of remeasurements immediately recognized in other comprehensive loss (3,581 ) (3,439 )
Summary of Amounts Recognized in Statement of Financial Position	As at December 31, in USD ‘000 2017 2016 Amounts recognized in the statement of financial position Defined benefit obligation (12,230 ) (9,201 ) Fair value of plan assets 9,131 6,369 Net liability (3,099 ) (2,832 )
Summary of Net Defined Benefit Liability	in USD ‘000 2017 2016 Change in defined benefit liability Net defined benefit liability at January 1, (2,832 ) (2,663 ) Defined benefit cost included in statement of comprehensive loss (409 ) 51 Total remeasurements included in other comprehensive loss (142 ) (599 ) Employer contributions 403 333 Currency translation effects (119 ) 46 Net defined benefit liability at December 31, (3,099 ) (2,832 )
Summary of Percentage of Assets Amount Contributed to Fair Value of Plan Assets	The detailed structures and assets held at December 31, 2016, are as follows: Plan assets As at December 31, 2016 Cash 2.7 % Bonds 65.2 % Shares 9.5 % Real estate 15.1 % Mortgages 7.4 % Alternative investments 0.1 % Total 100.0 %
Summary of Principal Actuarial Assumptions	The principal actuarial assumptions used were as follows: 2017 2016 Discount rate 0.80% 0.70% Salary increase (including inflation) 1.00% 1.00% Rate of pension increases 0.25% 0.25% Post-employment mortality table LPP 2015 G LPP 2015 G
Summary of Sensitivity Analysis of Group Defined Obligation	Sensitivity analysis illustrates the sensitivity of the Group defined benefit obligation at December 31, 2017 by varying the discount rate and the salary increase rate by plus / minus 50 basis points: in USD ‘000 Discount rate Discount rate Salary increase Salary increase Rate of pension increase Rate of pension increase Sensitivity analysis plus 50bps minus 50bps plus 50bps minus 50bps plus 25bps minus 25bps Discount rate 1.30 % 0.30 % 0.80 % 0.80 % 0.80 % 0.80 % Salary increase 1.00 % 1.00 % 1.50 % 0.50 % 1.00 % 1.00 % Rate of pension increases 0.25 % 0.25 % 0.25 % 0.25 % 0.50 % 0.00 % Defined benefit obligation (11,177 ) (13,471 ) (12,331 ) (12,135 ) (12,544 ) (11,934 ) Average duration of the defined benefit obligation 2017 2016 Duration in years 18.8 19.8

Shareholders' equity (Tables)

Shareholders' equity (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Classes Of Share Capital [Abstract]
Summary of Shareholders' Equity	Number of shares in USD ‘000 Common shares Preferred A shares Preferred B shares Non- voting shares Total shares Share capital Share premium Total January 1, 2016 2,215,434 7,706,777 11,079,549 347,113 21,348,873 1,694 99,597 101,291 Issuance of preferred A shares — 325,000 — — 325,000 26 2,366 2,392 Share issuance costs — — — — — — (33 ) (33 ) Issuance of non-voting shares to employees — — — 264,524 264,524 20 675 695 Offset of accumulated losses with share premium — — — — — — (30,639 ) (30,639 ) December 31, 2016 2,215,434 8,031,777 11,079,549 611,637 21,938,397 1,740 71,966 73,706 Number of shares in USD ‘000 Common shares Preferred A shares Preferred B shares Non- voting shares Total shares Share capital Share premium Total January 1, 2017 2,215,434 8,031,777 11,079,549 611,637 21,938,397 1,740 71,966 73,706 Conversion of preferred and non-voting shares 19,722,963 (8,031,777 ) (11,079,549 ) (611,637 ) — — — — Issuance of shares - IPO 6,450,000 — — — 6,450,000 496 96,254 96,750 Issuance of shares - PIPE 7,500,000 — — — 7,500,000 592 59,408 60,000 Issuance 454,548 — — — 454,548 36 3,671 3,707 Share issuance costs — — — — — — (11,964 ) (11,964 ) December 31, 2017 36,342,945 — — — 36,342,945 2,864 219,335 222,199
Summary of Authorized Share Capital	The authorized share capital that is not outstanding as at December 31, 2017 and December 31, 2016 is as follows: As at December 31, Number of shares 2017 2016 Authorized share capital 6 11,590,631

Operating expenses by nature (T

Operating expenses by nature (Tables)	12 Months Ended
	Dec. 31, 2017
Expense By Nature [Abstract]
Schedule of Operating Expenses by Nature	Year ended December 31, in USD ‘000 2017 2016 2015 External research and development costs 43,268 16,811 10,784 Staff costs (note 14) 17,999 7,436 7,313 Professional fees 2,862 4,016 743 Rents 592 427 367 Travel expenses 1,073 541 313 Patent registration costs 426 512 87 Depreciation 70 46 36 Other 1,190 374 203 Total operating expenses by nature 67,480 30,163 19,846
Summary of Depreciation Expense	The depreciation expense has been allocated as follows: Year ended December 31, in USD ‘000 2017 2016 2015 Research and development expenses 44 35 28 General and administrative expenses 26 11 8 Total depreciation 70 46 36

Staff costs (Tables)

Staff costs (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Staffing Costs [Abstract]
Summary of Staff Costs	Year ended December 31, in USD ‘000 2017 2016 2015 Wages and salaries 7,715 4,807 3,384 Social charges 993 443 337 Post-employment benefits expense 435 (51 ) 324 Share-based payments 8,856 2,237 3,268 Total staff costs 17,999 7,436 7,313

Income taxes and deferred tax38

Income taxes and deferred taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Income Tax [Abstract]
Schedule of Unrecorded Tax Losses Carry Forwards	The following details the tax losses carry forwards of the Company and their respective expiring dates. Expiring tax losses As at December 31, in USD ‘000 2017 2016 2020 2,925 2,808 2021 11,587 11,123 2022 16,253 15,602 2023 28,631 27,484 2024 58,596 — Total unrecorded tax losses carry forwards 117,992 57,017
Summary of Difference Between Income Tax Expense at Applicable Group Tax Rate and Effective Income Tax Expense	The following elements explain the difference between the income tax expense at the applicable Group tax rate and the effective income tax expense: Year ended December 31, 2017 in USD ‘000 ObsEva SA ObsEva USA Total Group Net loss before tax (65,397 ) (1,478 ) (66,875 ) Statutory tax rate (blended at Group level) 7.8 % 39.3 % 8.5 % Income tax credit at statutory tax rates (5,123 ) (581 ) (5,704 ) Tax impact of permanent differences 577 225 802 Temporary differences not recognized as deferred tax assets — 407 407 Tax on losses not recognized as deferred tax assets 4,546 — 4,546 Effective income tax expense — 51 51 Effective tax rate 0 % 3.5 % 0.1 % Year ended December 31, 2016 in USD ‘000 ObsEva SA ObsEva USA Total Group Net loss before tax (30,202 ) — (30,202 ) Statutory tax rate (blended at Group level) 7.8 % — 7.8 % Income tax credit at statutory tax rates (2,366 ) — (2,366 ) Tax impact of permanent differences 145 — 145 Tax on losses not recognized as deferred tax assets 2,221 — 2,221 Effective income tax expense — — — Effective tax rate 0 % 0 %

Loss per share (Tables)

Loss per share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Loss per Share	The basic loss per share is calculated by dividing the loss of the period attributable to the ordinary shares by the weighted average number of ordinary shares (common and non-voting) outstanding during the period as follows: Year ended December 31, 2017 Common shares Net loss attributable to shareholders(in USD ‘000) (66,926) Weighted average number of shares outstanding 29,799,047 Basic and diluted loss per share (in USD) (2.25) Year ended December 31, 2016 Preferred B shares Preferred A shares Common and non-voting shares Net loss attributable to shareholders (in USD ‘000) (15,516 ) (10,910 ) (3,776 ) Weighted average number of shares outstanding 11,079,549 7,790,475 2,695,898 Basic and diluted loss per share (in USD) (1.40 ) (1.40 ) (1.40 ) Year ended December 31, 2015 Preferred B shares Preferred A shares Common and non-voting shares Net loss attributable to shareholders (in USD ‘000) (2,380 ) (14,384 ) (3,102 ) Weighted average number of shares outstanding 1,274,910 7,706,777 1,661,231 Basic and diluted loss per share (in USD) (1.87 ) (1.87 ) (1.87 )

Share-based compensation (Table

Share-based compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Abstract]
Schedule of Recognized Share-based Payment Expenses	The total expenses arising from share-based payment transactions recognized during the period as part of staff costs were as follows: Year ended December 31, in USD ‘000 2017 2016 2015 Employee 2013 EIP 5,497 2,237 890 Employee 2017 EIP 3,359 — — Anti-dilution provisions — — 2,378 Total share-based compensation 8,856 2,237 3,268
Schedule of Vesting of Shares	The Group has no present obligation to repurchase or settle the shares in cash. 2017 2016 2015 Number of shares issued under the 2013 EIP 454,548 264,524 182,429 Average grant date fair value (in USD) — 11.37 2.48 Expense arising from the 2013 EIP (in USD ’000) 5,497 2,237 890
Movements in Number of Stock-options Outstanding Under 2017 EIP	Movements in the number of stock-options outstanding under the 2017 EIP were as follows: 2017 At January 1, — Granted 1,866,740 Forfeited — Exercised — At December 31, 1,866,740
Range of Exercise Prices and Expiry Dates Outstanding Stock-options	The outstanding stock-options have the following range of exercise prices and expiration dates: Range of exercise prices Expiration date 2020 USD 15.00 to USD 17.99 136,500 USD 12.00 to USD 14.99 31,950 USD 9.00 to USD 11.99 1,173,290 USD 6.00 to USD 8.99 525,000 Total outstanding options 1,866,740
Significant Inputs to Model to Determine Weighted Average Fair Value of Stock-options Granted	The weighted average fair value of the stock-options granted during the year ended December 31, 2017, determined using a Black-Scholes model was USD 6.98. The significant inputs to the model were: 2017 Weighted average share price at grant date USD 9.19 Weighted average strike price USD 9.19 Weighted average 10-year volatility 58 % Dividend yield 0 % Weighted average 10-year risk free rate 2.35 %

Commitments and contingencies (

Commitments and contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Commitments And Contingencies [Abstract]
Schedule of Operating Lease Commitments	Operating lease commitments As at December 31, in USD ‘000 2017 2016 Within 1 year 535 243 Later than 1 year and no later than 5 years 2,145 121 Later than 5 years 144 — Total 2,824 364

Related parties transactions (T

Related parties transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Transactions Between Related Parties [Abstract]
Summary of Total Remuneration Recorded for Members of the Board of Directors and Executive Committee	The following table sets forth the total remuneration recorded for members of the Board of Directors and Executive Committee: Year ended December 31, in USD ‘000 2017 2016 Short-term employee benefits (including base and variable cash remuneration) 3,403 1,890 Post-employment benefits 135 (18 ) Share-based payments 6,451 1,614 Total 9,989 3,486

General Information - Additiona

General Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017
Disclosure Of General Information About Financial Statements [Abstract]
Name of reporting entity	ObsEva SA
Date of foundation of entity	Nov. 14, 2012
Country of incorporation	Geneva, Switzerland
Details about operations of the entity	The Group is focused on the development and commercialization of novel therapeutics for serious conditions that compromise women’s reproductive health and pregnancy. The Group has a portfolio of three mid- to late-stage development in-licensed compounds (OBE2109, nolasiban and OBE022) being developed in four indications. The Group has no currently marketed products.

Accounting Principles Applied44

Accounting Principles Applied in the Preparation of the Consolidated Financial Statements - Summary of Useful Lives of Furniture Fixtures and Equipment (Detail)	12 Months Ended
	Dec. 31, 2017
Furniture [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Useful lives of furniture, fixtures and equipment	5 years
Hardware [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Useful lives of furniture, fixtures and equipment	3 years
Leasehold improvement [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Useful lives of furniture, fixtures and equipment	duration of lease

Accounting Principles Applied45

Accounting Principles Applied in the Preparation of the Consolidated Financial Statements - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017
Top of range [Member]
Disclosure of voluntary change in accounting policy [Line Items]
Estimated useful life of intangible assets	20 years

Accounting Principles Applied46

Accounting Principles Applied in the Preparation of the Consolidated Financial Statements - Schedule of Rates Used for Translation from Functional Currency to Presentation Currency (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Foreign Exchange Rates [Abstract]
Average rate (CHF)	0.9850	0.9624
Closing rate (CHF)	1.0160	1.0010

Accounting Principles Applied47

Accounting Principles Applied in the Preparation of the Consolidated Financial Statements - Summary of Geographical Analysis of Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Geographical Areas [Line Items]
Total non-current assets	$ 22,121	$ 16,819
Switzerland [Member]
Disclosure Of Geographical Areas [Line Items]
Total non-current assets	21,832	$ 16,819
USA [Member]
Disclosure Of Geographical Areas [Line Items]
Total non-current assets	$ 289

Accounting Principles Applied48

Accounting Principles Applied in the Preparation of the Consolidated Financial Statements - Summary of Geographical Analysis of Operating Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Geographical Areas [Line Items]
Total operating expenses	$ 67,480	$ 30,163	$ 19,846
Switzerland [Member]
Disclosure Of Geographical Areas [Line Items]
Total operating expenses	63,956	$ 30,163	$ 19,846
USA [Member]
Disclosure Of Geographical Areas [Line Items]
Total operating expenses	$ 3,524

Financial Risk Management - Sch

Financial Risk Management - Schedule of Sensitivity of Profit or Loss to Changes in Exchange Rates (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
EUR [Member]
Disclosure Of Financial Risk Management [Line Items]
Increase exchange rate vs CHF (2016) and USD (2017)	5.00%	5.00%
Increase effect on profit before tax	$ 924	$ 274
Increase effect on shareholders' equity	$ 924	$ 274
Decrease exchange rate vs CHF (2016) and USD (2017)	(5.00%)	(5.00%)
Decrease effect on profit before tax	$ (924)	$ (274)
Decrease effect on shareholders' equity	$ (924)	$ (274)
GBP [Member]
Disclosure Of Financial Risk Management [Line Items]
Increase exchange rate vs CHF (2016) and USD (2017)	5.00%	5.00%
Increase effect on profit before tax	$ 98	$ 193
Increase effect on shareholders' equity	$ 98	$ 193
Decrease exchange rate vs CHF (2016) and USD (2017)	(5.00%)	(5.00%)
Decrease effect on profit before tax	$ (98)	$ (193)
Decrease effect on shareholders' equity	$ (98)	$ (193)
CHF [Member]
Disclosure Of Financial Risk Management [Line Items]
Increase exchange rate vs CHF (2016) and USD (2017)	5.00%
Increase effect on profit before tax	$ 474
Increase effect on shareholders' equity	$ 474
Decrease exchange rate vs CHF (2016) and USD (2017)	(5.00%)
Decrease effect on profit before tax	$ (474)
Decrease effect on shareholders' equity	$ (474)
USD [Member]
Disclosure Of Financial Risk Management [Line Items]
Increase exchange rate vs CHF (2016) and USD (2017)		5.00%
Increase effect on profit before tax		$ 349
Increase effect on shareholders' equity		$ 349
Decrease exchange rate vs CHF (2016) and USD (2017)		(5.00%)
Decrease effect on profit before tax		$ (349)
Decrease effect on shareholders' equity		$ (349)

Cash and Cash Equivalents - Sch

Cash and Cash Equivalents - Schedule of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash And Cash Equivalents [Abstract]
Bank deposits	$ 110,841	$ 23,292
Interest bearing deposits		2,216
Total cash and cash equivalents	$ 110,841	$ 25,508	$ 54,275	$ 4,008

Cash and Cash Equivalents - S51

Cash and Cash Equivalents - Schedule of Percentage of Bank Held Cash and Cash Equivalents Split by Currency (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
CHF [Member]
Disclosure of cash and cash equivalents [Line Items]
Percentage of bank held cash and cash equivalents	6.00%	68.00%
USD [Member]
Disclosure of cash and cash equivalents [Line Items]
Percentage of bank held cash and cash equivalents	93.00%	20.00%
EUR [Member]
Disclosure of cash and cash equivalents [Line Items]
Percentage of bank held cash and cash equivalents	1.00%	10.00%
GBP [Member]
Disclosure of cash and cash equivalents [Line Items]
Percentage of bank held cash and cash equivalents		2.00%

Receivables and Payables - Addi

Receivables and Payables - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017
Within 1 year [Member]
Disclosure of receivables and payables [line items]
Contractual maturity of payables	1 year

Prepaid Expenses and Deferred53

Prepaid Expenses and Deferred Costs - Additional Information (Detail) $ in Millions	Dec. 31, 2016USD ($)
Prepaid Expense And Deferred Costs [Abstract]
Prepayments	$ 2.1
Deferred share issuance costs	$ 0.3

Furniture, Fixtures and Equip54

Furniture, Fixtures and Equipment - Schedule of Furniture, Fixtures and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about property, plant and equipment [Line Items]
Furniture, fixtures and equipment, Beginning balance	$ 121	$ 124
Additions	272	45
Depreciation charge	(70)	(46)
Currency translation effects		(2)
Furniture, fixtures and equipment, Ending balance	323	121
Total cost [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Furniture, fixtures and equipment, Beginning balance	223
Furniture, fixtures and equipment, Ending balance	495	223
Accumulated depreciation and amortization [Member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Furniture, fixtures and equipment, Beginning balance	(102)
Furniture, fixtures and equipment, Ending balance	$ (172)	$ (102)

Intangible Assets - Schedule of

Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about intangible assets [Line Items]
Net book value as at the beginning of the year	$ 16,608	$ 16,857
Additions	5,000
Currency translation effects		(249)
Net book value as at the end of the year	21,608	16,608
Total cost [Member]
Disclosure of detailed information about intangible assets [Line Items]
Net book value as at the beginning of the year	16,608
Net book value as at the end of the year	$ 21,608	$ 16,608

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($)	Apr. 25, 2017	Nov. 19, 2015	Aug. 28, 2013	Jun. 30, 2015	Dec. 31, 2017	Dec. 31, 2015	Dec. 31, 2016
Disclosure of detailed information about intangible assets [Line Items]
Intangible assets					$ 21,608,000	$ 16,857,000	$ 16,608,000
Purchase of intangible assets					5,000,000	$ 10,000,000
Additions					$ 5,000,000
Length of development cycle for intangible assets					20 years
Discount factor based on assumed cost of capital					15.00%
Merck Serono Licenses [Member]
Disclosure of detailed information about intangible assets [Line Items]
Purchase of intangible assets			$ 4,900,000
Additions				$ 2,400,000
Kissei License [Member]
Disclosure of detailed information about intangible assets [Line Items]
Upfront cash consideration to acquire in-license		$ 10,000,000
Recognition and payment of milestone amount	$ 5,000,000
Impairment loss					$ 0

Post- Employment Benefits - Sch

Post- Employment Benefits - Schedule of Defined Benefit Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Change in defined benefit obligation
Defined benefit obligation beginning balance	$ 2,832	$ 2,663
Current service cost	795	774
Interest cost	72	70
Currency translation effects	119	(46)
Remeasurements:
Impact of plan amendment	0	(512)
Effect of changes in demographic assumptions	0	316
Effect of changes in financial assumptions	(155)	203
Effect in experience assumptions	310	105
Defined benefit obligation ending balance	3,099	2,832
Present value of defined benefit obligation [Member]
Change in defined benefit obligation
Defined benefit obligation beginning balance	(9,201)	(7,765)
Current service cost	(795)	(774)
Interest cost	(72)	(70)
Net benefits paid	(1,604)	(643)
Currency translation effects	(403)	163
Remeasurements:
Impact of plan amendment	0	512
Effect of changes in demographic assumptions	0	(316)
Effect of changes in financial assumptions	155	(203)
Effect in experience assumptions	(310)	(105)
Defined benefit obligation ending balance	$ (12,230)	$ (9,201)

Post- Employment Benefits - S58

Post- Employment Benefits - Schedule of Fair Value of Plan Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Change in plan assets
Fair value of plan assets, beginning balance	$ (2,832)	$ (2,663)
Interest income	55	50
Employer contributions	403	333
Employee contributions	403	333
Currency translation effects	(119)	46
Remeasurements: return on plan assets (excluding interest income)	13	25
Fair value of plan assets, ending balance	(3,099)	(2,832)
Plan assets [Member]
Change in plan assets
Fair value of plan assets, beginning balance	6,369	5,102
Interest income	55	50
Employer contributions	403	333
Employee contributions	403	333
Net benefits paid	1,604	643
Currency translation effects	284	(117)
Remeasurements: return on plan assets (excluding interest income)	13	25
Fair value of plan assets, ending balance	$ 9,131	$ 6,369

Post- Employment Benefits - Sum

Post- Employment Benefits - Summary of Components of Defined Benefit Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Components of defined benefit cost
Current service cost	$ 795	$ 774
Interest cost	72	70
Interest income on plan assets	(55)	(50)
Employee contributions	(403)	(333)
Impact of plan amendment	0	(512)
Total included in staff costs	$ 409	$ (51)

Post- Employment Benefits - S60

Post- Employment Benefits - Summary of Remeasurement Components Recognized in Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Remeasurements recognized in other comprehensive loss
Effect of changes in demographic assumptions	$ 0	$ (316)
Effect of changes in financial assumptions	155	(203)
Effect in experience assumptions	(310)	(105)
Return on plan assets (excluding interest income)	13	25
Total remeasurements recognized as other comprehensive loss	(142)	(599)
Cumulative amount of remeasurements immediately recognized in other comprehensive loss	$ (3,581)	$ (3,439)

Post- Employment Benefits - S61

Post- Employment Benefits - Summary of Amounts Recognized in Statement of Financial Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Amounts recognized in the statement of financial position
Defined benefit obligation	$ (12,230)	$ (9,201)
Fair value of plan assets	9,131	6,369
Net liability	$ (3,099)	$ (2,832)

Post- Employment Benefits - S62

Post- Employment Benefits - Summary of Net Defined Benefit Liability (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Change in defined benefit liability
Fair value of plan assets, beginning balance	$ (2,832)	$ (2,663)
Defined benefit cost included in statement of comprehensive loss	(409)	51
Total remeasurements included in other comprehensive loss	(142)	(599)
Employer contributions	403	333
Currency translation effects	(119)	46
Fair value of plan assets, ending balance	$ (3,099)	$ (2,832)

Post- Employment Benefits - S63

Post- Employment Benefits - Summary of Percentage of Assets Amount Contributed to Fair Value of Plan Assets (Detail)	12 Months Ended
	Dec. 31, 2016
Percentage Of Assets Amount Contributed To Fair Value Of Plan Assets [Abstract]
Cash	2.70%
Bonds	65.20%
Shares	9.50%
Real estate	15.10%
Mortgages	7.40%
Alternative investments	0.10%
Total	100.00%

Post- Employment Benefits - S64

Post- Employment Benefits - Summary of Principal Actuarial Assumptions (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Defined Benefit Plans [Abstract]
Discount rate	0.80%	0.70%
Salary increase (including inflation)	1.00%	1.00%
Rate of pension increases	0.25%	0.25%
Post-employment mortality table	LPP 2015 G	LPP 2015 G

Post-Employment Benefits - Summ

Post-Employment Benefits - Summary of Sensitivity Analysis of Group Defined Obligation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Sensitivity Analysis For Actuarial Assumptions [Line Items]
Discount rate	0.80%	0.70%
Salary increase	1.00%	1.00%
Rate of pension increases	0.25%	0.25%
Average duration of the defined benefit obligation	18 years 9 months 18 days	19 years 9 months 18 days
Discount rate plus 50bps [Member]
Disclosure Of Sensitivity Analysis For Actuarial Assumptions [Line Items]
Sensitivity analysis	plus 50bps
Discount rate	1.30%
Salary increase	1.00%
Rate of pension increases	0.25%
Defined benefit obligation	$ (11,177)
Discount rate minus 50bps [Member]
Disclosure Of Sensitivity Analysis For Actuarial Assumptions [Line Items]
Sensitivity analysis	minus 50bps
Discount rate	0.30%
Salary increase	1.00%
Rate of pension increases	0.25%
Defined benefit obligation	$ (13,471)
Salary increase plus 50bps [Member]
Disclosure Of Sensitivity Analysis For Actuarial Assumptions [Line Items]
Sensitivity analysis	plus 50bps
Discount rate	0.80%
Salary increase	1.50%
Rate of pension increases	0.25%
Defined benefit obligation	$ (12,331)
Salary increase minus 50bps [Member]
Disclosure Of Sensitivity Analysis For Actuarial Assumptions [Line Items]
Sensitivity analysis	minus 50bps
Discount rate	0.80%
Salary increase	0.50%
Rate of pension increases	0.25%
Defined benefit obligation	$ (12,135)
Rate of pension increase plus 25bps [Member]
Disclosure Of Sensitivity Analysis For Actuarial Assumptions [Line Items]
Sensitivity analysis	plus 25bps
Discount rate	0.80%
Salary increase	1.00%
Rate of pension increases	0.50%
Defined benefit obligation	$ (12,544)
Rate of pension increase minus 25 bps [Member]
Disclosure Of Sensitivity Analysis For Actuarial Assumptions [Line Items]
Sensitivity analysis	minus 25bps
Discount rate	0.80%
Salary increase	1.00%
Rate of pension increases	0.00%
Defined benefit obligation	$ (11,934)

Post-employment Benefits - Addi

Post-employment Benefits - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Defined Benefit Plans [Line Items]
Expected contributions paid by employer under post-employment benefit plans	$ 403,000	$ 333,000
Post-employment benefit plans [Member]
Disclosure Of Defined Benefit Plans [Line Items]
Expected contributions paid by employer under post-employment benefit plans	$ 440,000

Shareholders' Equity - Summary

Shareholders' Equity - Summary of Shareholders' Equity (Detail) - USD ($) $ in Thousands	Feb. 23, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of classes of share capital [Line Items]
Beginning balance		21,938,397	21,348,873
Issuance of preferred A shares			325,000
Issuance of shares - IPO		6,450,000
Issuance of shares - PIPE		7,500,000
Issuance of shares - Incentive Plan		454,548
Issuance of non-voting shares to employees			264,524
Issuance of preferred A shares, value		$ 96,750
Issuance of shares - PIPE, value		60,000
Issuance of shares - Incentive Plan, value		36
Share issuance costs		$ (11,964)	$ (33)	$ (1,433)
Offset of accumulated losses with share premium	$ (30,600)
Ending balance		36,342,945	21,938,397	21,348,873
Share capital [Member]
Disclosure of classes of share capital [Line Items]
Equity, beginning balance		$ 1,740	$ 1,694
Issuance of preferred A shares, value		496	26
Issuance of shares - IPO- value		496
Issuance of shares - PIPE, value		592
Issuance of shares - Incentive Plan, value		36
Share issuance costs		0	0	$ 0
Issuance of non-voting shares to employees, value			20
Equity, ending balance		2,864	1,740	1,694
Share premium [Member]
Disclosure of classes of share capital [Line Items]
Equity, beginning balance		71,966	99,597
Issuance of preferred A shares, value		96,254	2,366
Issuance of shares - IPO- value		96,254
Issuance of shares - PIPE, value		59,408
Issuance of shares - Incentive Plan, value		3,671
Share issuance costs		(11,964)	(33)	(1,433)
Issuance of non-voting shares to employees, value			675
Offset of accumulated losses with share premium			(30,639)
Equity, ending balance		219,335	71,966	99,597
Total [Member]
Disclosure of classes of share capital [Line Items]
Equity, beginning balance		73,706	101,291
Issuance of preferred A shares, value			2,392
Issuance of shares - IPO- value		96,750
Issuance of shares - PIPE, value		60,000
Issuance of shares - Incentive Plan, value		3,707
Share issuance costs		(11,964)	(33)
Issuance of non-voting shares to employees, value			695
Offset of accumulated losses with share premium			(30,639)
Equity, ending balance		$ 222,199	$ 73,706	$ 101,291
Common shares [Member]
Disclosure of classes of share capital [Line Items]
Beginning balance		2,215,434	2,215,434
Conversion of preferred and non-voting shares		19,722,963
Issuance of shares - IPO		6,450,000
Issuance of shares - PIPE		7,500,000
Issuance of shares - Incentive Plan		454,548
Ending balance		36,342,945	2,215,434	2,215,434
Preferred A shares [Member]
Disclosure of classes of share capital [Line Items]
Beginning balance		8,031,777	7,706,777
Conversion of preferred and non-voting shares		(8,031,777)
Issuance of preferred A shares			325,000
Ending balance			8,031,777	7,706,777
Preferred B shares [Member]
Disclosure of classes of share capital [Line Items]
Beginning balance		11,079,549	11,079,549
Conversion of preferred and non-voting shares		(11,079,549)
Ending balance			11,079,549	11,079,549
Non voting shares [Member]
Disclosure of classes of share capital [Line Items]
Beginning balance		611,637	347,113
Conversion of preferred and non-voting shares		(611,637)
Issuance of non-voting shares to employees			264,524
Ending balance			611,637	347,113

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Oct. 13, 2017	Jan. 30, 2017	Feb. 23, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 26, 2018	Aug. 31, 2016
Disclosure of classes of share capital [Line Items]
Share capital				$ 2,864	$ 1,740
Number of shares issued and fully paid				36,342,945	21,938,397	21,348,873
Treasury non-voting shares				10,183	5,200
Issuance Of Issuance Of Non Vested Non Voting Shares Fully Paid				778,134	1,237,665
Issuance of non-voting shares to employees					611,637
Nominal value per share of non-voting shares					$ 0.0769
Share premium balance to offset the accumulated losses			$ 30,600
Share issue related cost				$ 11,964	$ 33	$ 1,433
Resolution of an Extraordinary General Meeting [Member]
Disclosure of classes of share capital [Line Items]
Authorized share capital							18,565,625
2013 Equity Incentive Plan [Member]
Disclosure of classes of share capital [Line Items]
Nominal value per share of non-voting shares				$ 0.0769
Issuance of shares				454,548	264,524
Common shares [Member]
Disclosure of classes of share capital [Line Items]
Share capital				$ 2,900
Number of shares issued and fully paid				36,342,945	2,215,434	2,215,434
Preferred A shares [Member]
Disclosure of classes of share capital [Line Items]
Number of shares issued and fully paid					8,031,777	7,706,777
Reclassified from share based payment reserve to the share premium								$ 2,400
Preferred A shares [Member] | Merck Serono [Member]
Disclosure of classes of share capital [Line Items]
Number of shares issued								325,000
Preferred B shares [Member]
Disclosure of classes of share capital [Line Items]
Number of shares issued and fully paid					11,079,549	11,079,549
IPO [Member]
Disclosure of classes of share capital [Line Items]
Issuance of non-voting shares to employees		6,450,000
Par value per share		$ 15
Nominal value per share of non-voting shares		$ 0.0769
Proceeds from issue of common shares		$ 96,800
Share issue related cost		$ 8,200
Private Placement [Member]
Disclosure of classes of share capital [Line Items]
Nominal value per share of non-voting shares	$ 0.0769
Proceeds from issue of common shares	$ 60,000
Share issue related cost	$ 3,700
Issuance of shares	7,500,000
Par value per share	$ 8

Shareholders' Equity - Summar69

Shareholders' Equity - Summary of Authorized Share Capital (Detail) - shares	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Authorized Share Capital [Abstract]
Authorized share capital	6	11,590,631

Revenue and Other Income - Addi

Revenue and Other Income - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)
Revenue and other income [Abstract]
Revenue	$ 0

Operating Expenses by Nature -

Operating Expenses by Nature - Schedule of Operating Expenses by Nature (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Expense By Nature [Abstract]
External research and development costs	$ 43,268	$ 16,811	$ 10,784
Staff costs (note 14)	17,999	7,436	7,313
Professional fees	2,862	4,016	743
Rents	592	427	367
Travel expenses	1,073	541	313
Patent registration costs	426	512	87
Depreciation	70	46	36
Other	1,190	374	203
Total operating expenses by nature	$ 67,480	$ 30,163	$ 19,846

Operating Expenses by Nature 72

Operating Expenses by Nature - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Expense By Nature [Abstract]
Research and development expense	$ 54,912	$ 23,711	$ 16,892

Operating Expenses by Nature 73

Operating Expenses by Nature - Summary of Depreciation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Depreciation Expense [Line Items]
Total depreciation	$ 70	$ 46	$ 36
Research and development expenses [Member]
Disclosure Of Depreciation Expense [Line Items]
Total depreciation	44	35	28
General and administrative expenses [Member]
Disclosure Of Depreciation Expense [Line Items]
Total depreciation	$ 26	$ 11	$ 8

Staff Costs - Summary of Staff

Staff Costs - Summary of Staff Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Defined Benefit Plans [Abstract]
Wages and salaries	$ 7,715	$ 4,807	$ 3,384
Social charges	993	443	337
Post-employment benefits expense	435	(51)	324
Share-based payments	8,856	2,237	3,268
Total staff costs	$ 17,999	$ 7,436	$ 7,313

Staff Costs - Additional Inform

Staff Costs - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017Employee	Dec. 31, 2016USD ($)Employee	Dec. 31, 2015Employee
Analysis Of Income And Expense [Abstract]
Average employed on full-time equivalents	32.3	22.4	16.2
Employed on full-time equivalents	37.7	25.3	19.9
Gain on post-employment benefits | $		$ 512

Income Taxes and Deferred Tax76

Income Taxes and Deferred Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Income Tax [Abstract]
Statutory tax rate (blended at Group level)	8.50%	7.80%
ObsEva Ireland Ltd [Member]
Disclosure of Income Tax [Abstract]
Current tax expense (income)	$ 0	$ 0
ObsEva USA Inc [Member]
Disclosure of Income Tax [Abstract]
Statutory tax rate (blended at Group level)	39.30%
Current tax expense (income)	$ 51,000	0
Deferred taxes	$ 0	0
Switzerland [Member]
Disclosure of Income Tax [Abstract]
Tax loss carryforward period	7 years
Current tax expense (income)	$ 0	0
Deferred taxes	$ 0	$ 0
Switzerland [Member] | Municipal and Cantonal Tax Rate [Member]
Disclosure of Income Tax [Abstract]
Statutory tax rate (blended at Group level)	22.60%
Switzerland [Member] | Federal Tax Rate [Member]
Disclosure of Income Tax [Abstract]
Statutory tax rate (blended at Group level)	8.50%

Income Taxes and Deferred Tax77

Income Taxes and Deferred Taxes - Schedule of Unrecorded Tax Losses Carry Forwards (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Total unrecorded tax losses carry forwards	$ 117,992	$ 57,017
2020 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Total unrecorded tax losses carry forwards	2,925	2,808
2021 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Total unrecorded tax losses carry forwards	11,587	11,123
2022 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Total unrecorded tax losses carry forwards	16,253	15,602
2023 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Total unrecorded tax losses carry forwards	28,631	$ 27,484
2024 [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items]
Total unrecorded tax losses carry forwards	$ 58,596

Income Taxes and Deferred Tax78

Income Taxes and Deferred Taxes - Summary of Difference Between Income Tax Expense at Applicable Group Tax Rate and Effective Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Income Tax [Line Items]
Net loss before tax	$ (66,875)	$ (30,202)	$ (19,867)
Statutory tax rate (blended at Group level)	8.50%	7.80%
Income tax credit at statutory tax rates	$ (5,704)	$ (2,366)
Tax impact of permanent differences	802	145
Temporary differences not recognized as deferred tax assets	407
Tax on losses not recognized as deferred tax assets	4,546	$ 2,221
Effective income tax expense	$ 51
Effective tax rate	0.10%	0.00%
ObsEva SA Member]
Disclosure Of Income Tax [Line Items]
Net loss before tax	$ (65,397)	$ (30,202)
Statutory tax rate (blended at Group level)	7.80%	7.80%
Income tax credit at statutory tax rates	$ (5,123)	$ (2,366)
Tax impact of permanent differences	577	145
Tax on losses not recognized as deferred tax assets	$ 4,546	$ 2,221
Effective tax rate	0.00%	0.00%
ObsEva USA Inc [Member]
Disclosure Of Income Tax [Line Items]
Net loss before tax	$ (1,478)
Statutory tax rate (blended at Group level)	39.30%
Income tax credit at statutory tax rates	$ (581)
Tax impact of permanent differences	225
Temporary differences not recognized as deferred tax assets	407
Effective income tax expense	$ 51
Effective tax rate	3.50%

Loss Per Share - Additional Inf

Loss Per Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
IPO closing date	Jan. 25, 2017
Anti-dilutive non-vested securities excluded from calculation of diluted earnings per share	778,134	1,237,662	623,145
Anti-dilutive impact of treasury stock on calculation of the diluted earnings per share excluded from calculation	10,183	5,200	80,353
Anti-dilutive impact of share options on calculation of the diluted earnings per share excluded from calculation	1,866,740	0	0

Loss Per Share - Schedule of Ba

Loss Per Share - Schedule of Basic and Diluted Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common shares [Member]
Earnings per share [Line Items]
Net loss attributable to shareholders	$ (66,926)
Weighted average number of shares outstanding	29,799,047
Basic and diluted loss per share	$ (2.25)
Preferred B shares [Member]
Earnings per share [Line Items]
Net loss attributable to shareholders		$ (15,516)	$ (2,380)
Weighted average number of shares outstanding		11,079,549	1,274,910
Basic and diluted loss per share		$ (1.40)	$ (1.87)
Preferred A shares [Member]
Earnings per share [Line Items]
Net loss attributable to shareholders		$ (10,910)	$ (14,384)
Weighted average number of shares outstanding		7,790,475	7,706,777
Basic and diluted loss per share		$ (1.40)	$ (1.87)
Common And Nonvoting Shares
Earnings per share [Line Items]
Net loss attributable to shareholders		$ (3,776)	$ (3,102)
Weighted average number of shares outstanding		2,695,898	1,661,231
Basic and diluted loss per share		$ (1.40)	$ (1.87)

Share-based Compensation - Sche

Share-based Compensation - Schedule of Recognized Share-based Payment Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Total share-based compensation	$ 8,856	$ 2,237	$ 3,268
Employee 2013 EIP [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Total share-based compensation	5,497	$ 2,237	890
Employee 2017 EIP [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Total share-based compensation	$ 3,359
Anti-dilution provisions [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Total share-based compensation			$ 2,378

Share-based Compensation - Addi

Share-based Compensation - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)shares	Dec. 31, 2017USD ($)sharesSFr / shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)$ / sharesshares	Nov. 30, 2015shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Total share-based compensation	$ 8,856,000		$ 2,237,000	$ 3,268,000
Impact on anti-dilution provisions	$ 0		$ 0
Founder [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Total share-based compensation				$ 2,400,000
Fair value of common shares | $ / shares				$ 2.68
Founder [Member] | Bottom of range [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Minimum diluted shareholding percentage	10.00%
Founder [Member] | Common shares [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Number of shares issued | shares					915,434
Founder [Member] | Common shares [Member] | Bottom of range [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Shares issued price per share | SFr / shares		SFr 0.077
Employee 2013 EIP [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Description of method of settlement for share-based payment arrangement	Upon enrollment in the 2013 EIP, Beneficiaries were granted a certain number of shares which they were entitled to acquire at a pre-determined price of 1/13 of a Swiss franc. The pre-determined price was generally paid by the Beneficiaries at the grant date and recognized as a pre-payment until the vesting period elapses resulting in the shares issuance being accounted for.
Description of vesting requirements for share-based payment arrangement	The shares generally fully vest over a four year vesting period, with 25% of the shares underlying the grant vesting after one year, and 1/48th of the shares underlying the grant vesting each month over a further period of three years.
Obligation to repurchase or settle shares	$ 0
Number of shares issued | shares	454,548	454,548	264,524	182,429
Total share-based compensation	$ 5,497,000		$ 2,237,000	$ 890,000
Employee 2017 EIP [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Description of vesting requirements for share-based payment arrangement	The stock-options vest under a 3-year or 4-year vesting schedule, have a 10-year expiration term and have a strike price equivalent to the share price at grant date.
Number of stock option, granted | shares	1,866,740
Stock options outstanding | shares	1,866,740	1,866,740
Stock options exercisable | shares	46,708	46,708
Total share-based compensation	$ 3,359,000
Employee 2017 EIP [Member] | Black-Scholes Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Description of option pricing model, share options granted	Black-Scholes model
Weighted average fair value of the stock-options granted	$ 6.98	SFr 6.98

Share-based Compensation - Sc83

Share-based Compensation - Schedule of Vesting of Shares (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Share-based payments	$ 8,856	$ 2,237	$ 3,268
Employee 2013 EIP [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Number of shares issued	454,548	264,524	182,429
Average grant date fair value (in USD)		$ 11.37	$ 2.48
Share-based payments	$ 5,497	$ 2,237	$ 890

Share-based Compensation - Move

Share-based Compensation - Movements in Number of Stock-options Outstanding Under 2017 EIP (Detail) - Employee 2017 EIP [Member]	12 Months Ended
	Dec. 31, 2017shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Granted	1,866,740
At December 31,	1,866,740

Share-based Compensation - Rang

Share-based Compensation - Range of Exercise Prices and Expiry Dates Outstanding Stock-options (Detail) - Employee 2017 EIP [Member]	12 Months Ended
	Dec. 31, 2017USD ($)shares
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Expiration date	2,020
Total outstanding options | shares	1,866,740
15.00 to 17.99 [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Total outstanding options | shares	136,500
15.00 to 17.99 [Member] | Bottom of range [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Range of exercise prices	$ 15
15.00 to 17.99 [Member] | Top of range [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Range of exercise prices	$ 17.99
12.00 to 14.99 [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Total outstanding options | shares	31,950
12.00 to 14.99 [Member] | Bottom of range [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Range of exercise prices	$ 12
12.00 to 14.99 [Member] | Top of range [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Range of exercise prices	$ 14.99
9.00 to 11.99 [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Total outstanding options | shares	1,173,290
9.00 to 11.99 [Member] | Bottom of range [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Range of exercise prices	$ 9
9.00 to 11.99 [Member] | Top of range [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Range of exercise prices	$ 11.99
6.00 to 8.99 [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Total outstanding options | shares	525,000
6.00 to 8.99 [Member] | Bottom of range [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Range of exercise prices	$ 6
6.00 to 8.99 [Member] | Top of range [Member]
Disclosure Of Range Of Exercise Prices Of Outstanding Share Options [Line Items]
Range of exercise prices	$ 8.99

Share-based Compensation - Sign

Share-based Compensation - Significant Inputs to Model to Determine Weighted Average Fair Value of Stock-options Granted (Detail) - Employee 2017 EIP [Member]	12 Months Ended
	Dec. 31, 2017USD ($)
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Weighted average share price at grant date	$ 9.19
Weighted average strike price	$ 9.19
Weighted average 10-year volatility	58.00%
Dividend yield	0.00%
Weighted average 10-year risk free rate	2.35%

Share-based Compensation - Si87

Share-based Compensation - Significant Inputs to Model to Determine Weighted Average Fair Value of Stock-options Granted (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Terms And Conditions Of Sharebased Payment Arrangement [Abstract]
Weighted average volatility period	10 years
Weighted average risk free period	10 years

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Operating Lease Commitments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Commitments and Contingencies [Line Items]
Total operating lease commitments	$ 2,824	$ 364
Within 1 year [Member]
Disclosure of Commitments and Contingencies [Line Items]
Total operating lease commitments	535	243
Later than 1 year and not later than 5 years [Member]
Disclosure of Commitments and Contingencies [Line Items]
Total operating lease commitments	2,145	121
Later than 5 years [member]
Disclosure of Commitments and Contingencies [Line Items]
Total operating lease commitments	$ 144	$ 0

Commitments and Contingencies89

Commitments and Contingencies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Disclosure of Commitments and Contingencies [Line Items]
License and supply agreement, undiscounted amount paid	$ 5
Royalty expiration period from the date of first commercial sale	15 years
Bottom of range [Member]
Disclosure of Commitments and Contingencies [Line Items]
License and supply agreement, potential undiscounted future payments	$ 0
Royalty payment as a percentage of net sales	20.00%
Top of range [Member]
Disclosure of Commitments and Contingencies [Line Items]
License and supply agreement, potential undiscounted future payments	$ 188

Related Parties Transactions -

Related Parties Transactions - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017DirectorMember
Disclosure of transactions between related parties [Line Items]
Number of directors | Director	8
Numbers of executive committee members | Member	6
Other Related Parties [Member]
Disclosure of transactions between related parties [Line Items]
Description of other significant transactions with related parties	There were no other significant transactions with related parties during the years presented.

Related Parties Transactions 91

Related Parties Transactions - Summary of Total Remuneration Recorded for Members of the Board of Directors and Executive Committee (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Transactions Between Related Parties [Abstract]
Short-term employee benefits (including base and variable cash remuneration)	$ 3,403	$ 1,890
Post-employment benefits	135	(18)
Share-based payments	6,451	1,614
Total	$ 9,989	$ 3,486