You’ve been trying to conceive and are about to take a home pregnancy test. As you excitedly tear open the packaging, you notice a date on the side of the box. And it’s from … last month. Is your pregnancy test expired? And does that mean you can’t use it?
Home pregnancy tests are up to 99 percent accurate when used correctly. But there are some things that can throw off your results — and that little date stamp on the packaging is one of them. Here’s what you should know about pregnancy test expiration dates and the best time to take a pregnancy test.
Do pregnancy tests expire?
Yes. Like many of the other items in your medicine cabinet, pregnancy tests don’t last forever and do expire.
To understand why, it helps to know a little bit about how they work. Pregnancy tests work by measuring levels of the pregnancy hormone human chorionic gonadotropin (hCG). HCG starts showing up in a woman’s urine (and her blood) within six to 12 days after fertilization, and her levels go up every day after that, peaking between 7 and 12 weeks of pregnancy.
The test strips on pregnancy tests contain a chemical that detects the hCG in a woman’s urine to confirm that she’s pregnant. But the chemical has a shelf life, and after the test’s expiration date, it becomes less effective at detecting hCG. As a result, the pregnancy test is more likely to give you an inaccurate reading. False negatives are more likely, but it’s also possible to get a false positive.
In short, pregnancy tests do expire. And using one past the expiration date could give you an inaccurate result.
When do pregnancy tests expire?
Most pregnancy tests last for two to three years. But that doesn’t necessarily mean a test will be good for that long after you buy it. All tests have an expiration date stamped on the packaging — but that date is two to three years from when the test was manufactured. So if a test was sitting on the store shelf for a while before you bought it, the expiration date might be less than two to three years away.
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The lesson? Always check the expiration date before buying. And if you have a pack on hand for a while, look at the expiration date again before you actually take one of the tests. If it’s expired, throw it out.
One other thing to keep in mind: You can only count on a test’s expiration date if the test has been stored correctly. Excessive heat or humidity can cause pregnancy tests to degrade faster, and it’s possible for them to go bad before the date printed on the label.
Keeping your test in a dry, room-temperature space (like the bathroom) is just fine. And if you’re concerned, the test will list appropriate storage conditions right on the packaging.
Do expired pregnancy tests work?
An expired pregnancy test could give you an accurate result, but experts agree that you shouldn’t take a chance. In general, pregnancy tests that are past their expiration date are more likely to give you a false negative or a false positive reading. So it’s not a good idea to use them.
When should you take a pregnancy test?
You can take a pregnancy test anytime before the use-by date listed on the package. To increase your chances of a reliable reading, wait at least until the day of your expected period to test. And be sure to follow the instructions on the packaging.
Is it okay to buy a box of pregnancy test sticks or strips in advance while you’re trying to conceive?
Absolutely. It’s fine to keep a package around for a few weeks, a few months, or even longer — as long as you check the expiration date before you use a test. If it hasn’t passed yet, you’re in the clear.
The bottom line is that all home pregnancy tests have an expiration date, and using an expired test can increase the chance of getting an inaccurate result. The date is stamped right on the packaging, so check it before you buy the test. And if you don’t open the package to use one right away, check the date again before using it to see whether you're pregnant or not.
No matter what your test result turns out to be, you'll need to get your pregnancy confirmed by your OB/GYN or midwife anyway. But it's best to try for the most accurate reading possible before you make your appointment, for your own information and peace of mind as much as anything. And if you have any questions at all about taking a pregnancy test or reading the results, check in with your practitioner.
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