- There are two types of pregnancy tests: urine and blood. But you should only worry about at-home urine pregnancy tests expiring.
- The way at-home pregnancy tests work is that they are coated in a special type of lab-made antibody which detects the presence of the pregnancy hormone, hCG. But these antibodies will evaporate over time making the test less accurate.
- At-home pregnancy tests should come with an expiration date on the box, which is usually two to three years after the date of manufacture.
- If you take an expired pregnancy test, you have a good chance of getting a false negative result, which is when the test tells you that you’re not pregnant when you are, in reality.
- This article was reviewed by Julia Simon, MD, who is an assistant professor with the Department of Obstetrics and Gynecology at UChicago Medicine.
- Visit Insider’s homepage for more stories.
There are two types of pregnancy tests: urine and blood. Both test for the hormone called human chorionic gonadotropin (hCG), which you start producing after implantation. But only one test expires.
Pregnancy tests will expire in a couple of years
Blood pregnancy tests do not expire because analysis happens in a laboratory rather than at home. You can get one at a doctor’s office, where they will draw a blood sample to be sent out for testing.
However, the more common urine pregnancy tests, which you can pick up at your local pharmacy, can and do expire.
The way pregnancy tests work is that they are coated in a special type of lab-made antibody. Normally, antibodies are proteins that our immune systems produce to fend off infection and disease. But we can also synthesise antibodies in the lab for many different types of tests that can diagnose everything from infectious diseases to pregnancy.
The antibodies in home pregnancy tests react specifically to hCG, but will slowly evaporate and become less effective over time.
“Like many pharmaceuticals, pregnancy tests last for two to three years,” says Dr. Paul Blumenthal, MD, an OB-GYN and Professor at Stanford University whose research includes pregnancy tests.
However, this does not mean that the test will last for two years after you buy it, Blumenthal says. It may have spent a considerable amount of time sitting on a store shelf. So, you should always refer to the expiration date on the package to be certain.
Certain conditions can also affect how quickly pregnancy tests expire. It is generally recommended to store pregnancy tests at room temperature, or at least between 36 and 86 degrees Fahrenheit. If you leave your test in a blistering hot or freezing cold car, for example, it might be safer to buy a new one.
What happens if you take an expired pregnancy test
Because urine tests become less sensitive over time, they will eventually lose their ability to detect pregnancy entirely. This means if you use an expired pregnancy test, you are more likely to get an inaccurate result.
Most likely, you’ll get a false negative, which is when your test says you’re not pregnant but you are. While less common, you can also receive a false positive, when the test says you’re pregnant but you’re not.
It’s possible that you can still get an accurate result from an expired pregnancy test – especially if you’re more than a few weeks into your pregnancy and your hCG levels are really high, Blumenthal says.
But he adds that it’s best not to chance it and just stick with pregnancy tests that are not past their expiration date. “Avoid using expired tests if at all possible,” Blumenthal says.
If you are feeling the symptoms of early pregnancy (nausea and vomiting or breast tenderness for example,) but your pregnancy test comes out negative, this may be a good time to double-check the expiration date on the box or go get tested at your doctor’s office.
Related stories about pregnancy and pregnancy tests:
- When to take a pregnancy test for the most accurate result
- Home pregnancy tests are very accurate if you use them correctly
- Pregnancy symptoms you can expect each trimester of your pregnancy and how to alleviate them
- Yes, you can get a flu shot while pregnant. Here’s the best time to get it.
- Doctors debunk the 25 biggest pregnancy myths
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