Pregnancy tests can detect pregnancy as early as 6 to 8 days after ovulation, which is roughly 5 to 6 days before a missed period for some very sensitive tests. These tests detect the hormone hCG (human chorionic gonadotropin), which starts to be produced after the fertilized egg implants into the uterine wall, typically 6 to 10 days after ovulation. Blood tests can detect pregnancy slightly earlier than urine tests because they measure smaller amounts of hCG. Generally, pregnancy tests are more accurate from the day of the expected period or the first missed period, with most home pregnancy tests being over 99% accurate at that point. Key points:
- Implantation occurs about 6 to 10 days after ovulation, leading to hCG production.
- Sensitive home urine pregnancy tests can detect hCG 5 to 6 days before a missed period.
- Blood tests can detect hCG around 6 to 8 days after ovulation, detecting pregnancy earlier than urine tests.
- Testing too early may give a negative result even if pregnant, so retesting after the missed period is recommended.
- For best accuracy, testing with the first morning urine is advised, especially before the missed period.
This makes it possible for some high-sensitivity tests to detect pregnancy nearly a week before a missed period, though accuracy increases closer to the expected period date.
