If you’ve had unprotected sex recently, then you might be wondering if you’re pregnant. And asking questions like, ‘how long do I need to wait before taking a pregnancy test?’ and ‘How do I make sure I’m getting the most accurate results?’ To answer those Qs (and more), we spoke to Dr. Anna Whelan, an OB-GYN and maternal-fetal medicine fellow at the Women and Infants Hospital of Rhode Island.
How soon after unprotected sex can I test for pregnancy?
Rule of thumb: For the most accurate results, wait a minimum of two weeks after having unprotected sex to take a home pregnancy test, said Dr. Whelan. Because your body needs time to build up hCG, the hormone that’s produced during pregnancy and detected by pregnancy tests. If you take a pregnancy test too early, there’s a chance you could get a false negative.
How soon can a blood test detect pregnancy?
Blood tests are more sensitive than pregnancy tests, and can detect lower levels of hCG than at-home tests. So they can determine if you’re pregnant seven to 10 days after conception. But you have to see a doctor to get a blood test. And it can take longer to get results due to lab processing, said Dr. Whelan. Doctors typically perform them after you get positive results from a home pregnancy test.
How accurate are pregnancy tests?
Both types of pregnancy tests are pretty precise. An at-home test is 97% to 99% accurate when used correctly (more on that below). A blood test is around 99% accurate.
If you get a positive result at home, call your doctor. Your provider can help you confirm the pregnancy. And keep in mind: It’s rare to get a false positive result. So even if the lines on the test are faint, it likely means you’re pregnant.
How can I make sure the pregnancy test results are as accurate as possible?
There are a few things that experts recommend you do:
Take the test in the morning. That’s when hCG is the most concentrated in your urine, said Dr. Whelan.
Read your results at the right time. Follow the instructions on the package closely. Checking the results too early or too late can lead to an incorrect result.
Avoid drinking too much water or other liquids beforehand. Diluting your urine could interfere with the test’s ability to detect your hCG levels properly.
Store the test correctly. Specifically between 36 and 86 degrees Fahrenheit. That'll help slow down the expiration process. Speaking of which...
Double check the expiration date. Because the antibody coating on a pregnancy test can begin to evaporate and lose its effectiveness over time. At-home tests typically last about one to three years after manufacturing.
Of course you want to know as soon as you can if you’re pregnant. But to get the most accurate results, it’s best to wait at least two weeks after having unprotected sex before taking a pregnancy test. And if you’re confused or concerned about your test results, talk to your doctor.
Updated on Jan. 18 to reflect new information.
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