Yet another cycle, and still no big fat positive (BFP). But, this time you feel differently…like you might, possibly, “pretty please”, be pregnant. A little bit of spotting, tender and swollen breasts, a funky food craving here and there… of course, you know that these early signs of pregnancy can also be just run of the mill PMS symptoms, but something feels different this time. Is it possible that the pregnancy test you took produced a false negative?
The simple answer to your question is: yes, absolutely. There are at least three reasons for a pregnancy test false negative.
Testing too early: Home pregnancy tests work by detecting the presence of hCG (human chorionic gonadotropin) in your urine. Following conception, the growing placenta will begin to secrete hCG as soon as the embryo implants into the wall of the uterus, which occurs approximately 7-10 days post ovulation. Even though the levels of hCG increase rapidly in these first days (they will double every 48-72 hours), if you take a pregnancy test at day 6 or 7 post ovulation, it is highly possible, even if you have conceived, that you will not yet have enough hCG present in your urine to get a positive result. A negative result in these early days could definitely be a false negative.
Test sensitivity too low: As you probably already know, home pregnancy tests come in lots of “shapes and sizes.” There are test strips and midstream tests and digital tests. And, HPTs have different sensitivities as well. Some HPTs are highly “sensitive” to hCG and are calibrated to detect a relatively low amount of hCG, like 20 mIU/ml. On the other hand, other HPTs have a low sensitivity to hCG and are calibrated to detect a much higher amount of hCG, 50 mIU/ml or 100 mIU/ml for example. A newly pregnant women might have 50 mIU/ml of hCG by 7 days post ovulation. If you are just 7 days post ovulation and you test with an HPT calibrated to detect 100 mIU/ml, the test will be negative.
Urine too diluted: Women who drink lots of water and/or urinate frequently may not realize that they are lowering the amount of hCG that is detectable in the urine. If you received a negative result on a pregnancy test, try testing again using first morning urine, as this will have the most concentrated amounts of hCG.
Fortunately it is easy to determine if you were the victim of a pregnancy test false negative. Simply test again in a couple of days. For very best results, be sure to test using first morning urine and a highly sensitive early pregnancy test.
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