Taking a pregnancy test can be a nerve-racking moment, regardless of which outcome you'd prefer. Wanting to ensure that it is as accurate as possible is a normal feeling, and typically, they can be very accurate when used correctly. So, you've read the instructions, followed them closely, and checked the expiration date. Wait, can a pregnancy test expire? As it turns out, they can.
According to the American Pregnancy Association (APA), home pregnancy tests work by containing a special chemical that reacts with the presence of a hormone called human chorionic gonadotropin (hCG). The hCG hormone builds up rapidly in your body in the first few days of pregnancy, and can be detected in your urine by home pregnancy tests. As Parents mentioned, the home pregnancy tests contain antibodies coated with a chemical that bonds to hCG if it's present, delivering a positive result. If the molecules do not bond with any hCG, you get a negative result.
At-home urine tests can be 97 percent effective when used properly. However, if used incorrectly or taken too early, they can provide an inaccurate result. One of the things that can yield an inaccurate result is a home pregnancy test that is past its expiration date, as noted by Parents.
According to Self, an expired home pregnancy test is one of the most common reasons for receiving an inaccurate test result. When a test is past its expiration date, the chemical that detects hCG is not liable to work as it should. Though there is no way to really tell right away if the result is accurate or not, due to the chemical's probable shelf life, it may not be. For best results, it's always smart to check the expiration date on the test package first.
Checking in with your OB-GYN for a follow-up test can ensure the most accurate results. But just like your milk, you should always check the expiration date on any pregnancy tests. (OK, not just like your milk — only pee on pregnancy tests.)