| Cover | Aug. 30, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 30, 2021 |
| Entity File Number | 001-40606 |
| Entity Registrant Name | SERA PROGNOSTICS, INC. |
| Entity Central Index Key | 0001534969 |
| Entity Tax Identification Number | 26-1911522 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 2749 East Parleys Way |
| Entity Address, Address Line Two | Suite 200 |
| Entity Address, City or Town | Salt Lake City |
| Entity Address, State or Province | UT |
| Entity Address, Postal Zip Code | 84109 |
| City Area Code | 801 |
| Local Phone Number | 990-0520 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class A Common Stock, $0.0001 par value per share |
| Trading Symbol | SERA |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
