how soon after conception does a pregnancy test work

6 minutes ago 1
Nature

A pregnancy test can detect hCG, the pregnancy hormone, only after implantation takes place and enough hormone has built up in the urine. In practice:

  • Earliest tests: Some highly sensitive home tests may show a positive result as early as about 8–10 days after ovulation or around 4–7 days before a missed period, but this varies widely and isn’t guaranteed. For many people, a positive result is more reliably detected about 10–14 days after ovulation or after a missed period.
  • Most reliable timing: Waiting until the first day of a missed period gives the best balance of accuracy and timeliness for a home test. Even then, a small percentage (often up to around 5–10%) may still get a negative result if testing very early.
  • How to interpret: If you test early and get a negative result but your period is late, repeat the test a few days later. If pregnancy is unlikely but your period remains absent, consider consulting a clinician to rule out other issues.

Key points to help plan:

  • If you know your ovulation date, testing about 10–14 days after that date is a common window for a reliable result. If you don’t know ovulation, test after you miss a period.
  • Blood tests for pregnancy (done in a clinic) can detect pregnancy earlier than urine tests, but these are not home tests. They may detect hCG earlier than urine tests in some cases.

If you’d like, I can tailor this to your typical cycle length and estimate a personalized testing window.