How Early Can You Take a Pregnancy Test?

If you’ve been part of the TTC community for a while, you are probably familiar with the dreaded “two-week wait”, those a-g-o-n-i-z-i-n-g-l-y, l-o-n-g days between ovulation and the date until your next period is supposed to start. Generations of women before us would never have even considered taking a pregnancy test before they missed at least one period. But, modern technology has given trying-to-conceive women many tools to help with fertility: the electronic fertility monitor, the digital basal thermometer, and the early detection home pregnancy test! At least in theory, these early detection tests can decrease some of the anxiety for trying to conceive women by shortening the two-week wait by a few days.

So, how early can you take a pregnancy test? Before we answer this question, a quick refresher on the chronology of ovulation, conception, and implantation might be helpful, as well as some information on the hormone hCG and home pregnancy tests. Once the dominant follicle ruptures and releases the egg from the ovary into the nearby Fallopian tube, you have up to 24 hours for that egg to be fertilized. Assuming a healthy, vibrant sperm cell is waiting eagerly in the Fallopian tube and is able to penetrate the fresh egg, conception will occur! Over the next several days, this newly fertilized egg (now called an embryo) will journey down through the Fallopian tube into the uterus and begin to implant itself into the uterine lining. Once implantation occurs (which, according to most research findings, happens 6-12 days after ovulation), the placenta will begin to secrete hCG (human chorionic gonadotropin), the so-called “pregnancy hormone”.

In the first few weeks after implantation, the amount of hCG that is secreted doubles every 48-72 hours, which means that the level of hCG in a pregnant woman’s body quickly increases from almost nothing (a non-pregnant woman has less than 5 mIU/ml) to quite a lot in just a few days. By 7 or so days post ovulation, a pregnant woman will have up to 50 mIU/ml of hCG circulating in her blood. As you might already know, urine-based home pregnancy tests (and blood pregnancy tests performed at a clinic) work by detecting the presence of hCG, and the sensitivity of available HPTs vary significantly. For example, you can choose from HPTs that are calibrated to detect 20 mIU/ml, 50 mIU/ml and over 100 mIU/ml of hCG.

How early can you take a pregnancy test? Based on the information above, it is safe to assume that most (but not all) newly pregnant women will have a sufficient amount of hCG by 7 to 10 days post ovulation to confirm pregnancy with a highly sensitive home pregnancy (for example, a test calibrated to detect 20 mIU/ml of hCG. It is important to note, however, that testing this early can result in a false negative, especially if you ovulated later than you thought, your hCG production is on the low end of normal, or if implantation has not occurred yet. If you decide to test as early as 7 days post ovulation and you get a negative result, we recommend testing again in a few days, just to be sure! Therefore, the simple answer to the “how early can you take a pregnancy test” question is between 7 and 10 days after ovulation …much better than waiting a full two weeks!

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