Pregnancy Tests and hCG Hormone Levels
As noted on our products page, our pregnancy tests detect the hCG hormone. Because hCG is secreted by developing placental tissue, it's very reliable indicator that a pregnancy has taken place. One of the most common customer support questions we receive is: "When can I begin testing for pregnancy during my cycle?" To understand when, let's take a look at the general timeline of events that take place once ovulation occurs. As noted above, when conception (the meeting of egg and sperm) takes place, the embryo is still "free-floating" in the space of the mother's womb. hCG only starts flowing following implantation. Typically, implantation of the embryo takes place a handful of days after conception - around six days or so on average. Once the embryo implants, hCG is rapidly produced and doubles in early pregnancy every two to three days. Hence, the rate in which hCG increases is very rapid, nearly exponential. This is called hCG doubling time.
With 20 mIU/ml/hCG pregnancy tests (high sensitivity), you can typically begin testing at around seven to ten days past ovulation. On average, this is when the hCG level in a woman's urine starts to exceed the 20mIU/ml/hCG threshold. Do note that "average" does not mean "everybody"! A negative test result this early in pregnancy (7 to 10 DPO) is not necessarily conclusive: hCG develops at different rates among women, and for some women hCG develops slowly. Follow up tests are recommended every 24 to 48 hours using a first morning urine sample. First morning urine will yield the highest volumes of the "pregnancy hormone". Once you determine a positive result on a home pregnancy test, follow up with doctor.... and congratulations!