What’s the earliest a pregnancy can be detected?
For most women, it may be possible to determine whether you are pregnant as early as 7-10 days after conception. However, the time required depends greatly on the type of pregnancy test being used, as well as your own individual physiology.
Clinical blood and urine tests, performed by your health care provider, may be more accurate and produce an earlier positive than home pregnancy tests. However, these tests can be expensive, inconvenient, and time consuming. For this reason, many women choose to use home pregnancy tests.
Home pregnancy tests measure the amount of the pregnancy hormone hCG (Human Chorionic Gonadotropin) present in a woman’s system. As a pregnancy progresses, the amount of hCG present in a womans urine increases. At 10 days past conception, for example, the average woman has an hCG measurement of right around 25 mIU. This amount doubles to 50 mIU at 12 days past conception, and then doubles again to 100 mIU at around two weeks past conception. Different tests have different levels of sensitivity; if you use a home pregnancy test that is sensitive to 100 mIU, it will not tell you that you are pregnant if your level of hCG is only 75 mIU.
In addition, the rate at which hCG shows up in the system varies from one woman to the next. For this reason, if you test early with a very sensitive test, you could still wind up with a false negative. You should follow up this early test with an additional test a few days later.
hCG is most concentrated in the first morning urine of the day, so it is important to test during this time.