A blood test can typically detect pregnancy 6 to 12 days after conception, often before a missed period, by measuring the hormone human chorionic gonadotropin (hCG) in the bloodstream. This is earlier than urine-based home pregnancy tests, which generally detect pregnancy around the time of a missed period.
Details on Blood Test Detection
- Blood tests detect hCG as low as 1–5 mIU/mL, allowing for earlier and more sensitive detection compared to urine tests that detect higher thresholds (20–50 mIU/mL).
- Quantitative blood tests measure exact hCG levels, providing information on pregnancy progression or identifying complications such as ectopic pregnancy or miscarriage.
- The hormone hCG starts increasing after implantation, which occurs about 6–12 days post-conception, explaining the early detection window.
Summary
| Pregnancy Test Type | Earliest Detection Time After Conception | Sensitivity |
| Blood hCG Test | 6-12 days | Detects 1–5 mIU/mL of hCG |
| Urine Pregnancy Test | About 14 days (at missed period) | Detects 20–50 mIU/mL of hCG |
Blood tests are recommended when early confirmation or precise hCG tracking is needed, such as in fertility treatments or early pregnancy complications.
If testing too early, repeat tests may be advisable to confirm pregnancy status.
