An ad for tampons pops up on your social media feed. You glance at the calendar, realize you’re feeling more tired than usual and wonder, “When was my last period?”
Without fail, these moments always seem to happen after the drugstore has closed. So you dig through your bathroom drawer and find it: a pregnancy test you bought last year.
You might ask yourself, “Can pregnancy tests expire?” Yes, they can. Here’s why.
Why do pregnancy tests expire?
First, here’s a quick lesson on how home pregnancy tests work. Home pregnancy tests detect levels of the hormone hCG (human chorionic gonadotropin) in your urine. Your body begins producing hCG once a fertilized egg implants in your uterine wall.
Pregnancy tests work by using antibodies to bind hCG and produce a reaction, which results in a color change. This traditionally occurs with the appearance of marker lines, or in the case of the Clearblue® Digital Pregnancy Test, the reaction is read by an optical sensor, which then displays the result as the words “Pregnant” or “Not pregnant” (in words) on an LCD screen.1, 2
The antibodies used in home pregnancy tests to detect hCG don’t last forever — hence the expiration date. Once a test has hit its expiration date (typically one to three years after it was manufactured) the antibodies aren’t as good at detecting hCG. And that can cause problems, particularly in the form of false negatives.
How do I know if my pregnancy test has expired?
All Clearblue® pregnancy tests have clearly marked expiration dates on the bottom of the box and on the foil wrapper of each test. So it’s fine if you take tests out of the box and then discard it, but you should never unwrap a test until you’re ready to use it. Clearblue® pregnancy tests are meant to be stored in their foil wrappers until they’re ready to be used immediately.
The expiration date is based on when the test was manufactured. It’s important to check the expiration date when you buy your test as the expiration date may be sooner than you expect. Make sure to check the expiration date every time you test as well. A two-pack of tests you purchased more than a year ago could have unexpectedly expired.
Do expired pregnancy tests work?
Once a pregnancy test expires, the antibodies it uses to detect hCG levels begin to break down. This means the test may not be able to detect hCG levels that a nonexpired pregnancy test could, which could lead to a false negative result. A false negative can delay decision making, lifestyle changes and care.
You may be wondering if an expired pregnancy test can result in a false positive. Pregnancy tests work by detecting the hCG hormone, which is usually only present if you’re pregnant. False positives are extremely rare. If you use an expired pregnancy test and it’s positive, chances are you’re pregnant. But because the test was expired, it’s not considered accurate and you need to test again with a non-expired test. Whenever you see a positive result, whether the test is expired or not, it’s important that you see your healthcare professional.
So the next time you’re cleaning out your bathroom drawers, check the expiration dates on any home pregnancy tests you have on hand. Make sure to store your tests appropriately and take the tests as per usage instructions. This includes being mindful of expiration dates. Disposing of expired tests will give you some peace of mind and ensure accuracy the next time you need to test.
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- Gnoth, C., & Johnson, S. (2014). Strips of Hope: Accuracy of Home Pregnancy Tests and New Developments. Geburtshilfe und Frauenheilkunde, 74(7), 661–669. https://doi.org/10.1055/s-0034-1368589.
- Kelly L. Scolaro, Pharm.D., Kimberly Braxton Lloyd, Pharm.D., Kristen L. Helms, Pharm.D., Devices for home evaluation of women’s health concerns, American Journal of Health-System Pharmacy, Volume 65, Issue 4, 15 February 2008, Pages 299–314, https://doi.org/10.2146/ajhp060565.