Home pregnancy tests can detect pregnancy by measuring the hormone human chorionic gonadotropin (hCG) in urine, which starts being produced after a fertilized egg implants in the uterus. How early can pregnancy tests detect pregnancy?
- Trace levels of hCG can be detected as early as 6 to 8 days after ovulation, which is roughly 6 days before a missed period for some sensitive tests
- Some of the most sensitive home pregnancy tests, such as Clearblue Early Detection and First Response Early Result, claim to detect pregnancy up to 6 days before the missed period, with about 77-78% accuracy at that point
- Accuracy increases as you approach the day of your expected period, with over 99% accuracy from the day your period is missed
- Blood tests by healthcare providers can detect pregnancy even earlier, about one week before a missed period, as they measure hCG levels in the blood
Important considerations:
- Testing too early may result in a false negative because hCG levels might not be high enough yet to detect
- For best results, test with the first morning urine when hCG concentration is highest, and avoid excessive fluid intake before testing to prevent dilution
- If you get a negative result but still suspect pregnancy, it is recommended to wait a few days and test again
- If you do not know when your next period is due, the NHS recommends testing at least 21 days after unprotected sex for reliable results
In summary, with the most sensitive home pregnancy tests, you can potentially detect pregnancy as early as 6 days before your missed period, but testing closer to or after the missed period provides more reliable results. Blood tests can detect pregnancy slightly earlier than urine tests
