When you’re trying to get pregnant, the time that you have to wait after ovulation to see if things, well, worked can feel like months. Conversely, if you’re on the missed-period-and-panicking train, there is nothing more nerve-wracking than the few minutes you wait for an at-home pregnancy test result to appear.
The reality is, even though pregnancy tests are more accurate than ever before, you won’t be able to get a result immediately after you have sex to find out whether you’re pregnant.
How Pregnancy Tests Work
When we talk about how soon you should take a pregnancy test after unprotected sex, it helps to understand exactly how pregnancy tests actually work. At-home pregnancy tests are activated by a hormone called beta hCG, which gets secreted when you’re pregnant. “A pregnancy test is testing how much of that beta hCG is in your urine,” says Dr. Catherine Caponero, obstetrician and gynecologist at Cleveland Clinic. She says that this hormone can build up to high enough levels to give you a positive result within six to 10 days after conception.
How Soon Should You Take a Pregnancy Test After Unprotected Sex?
“The earliest I would recommend taking a home pregnancy test is seven to 10 days after ovulation, and you should ideally have sex 24 to 72 hours prior to ovulation for the best chance to become pregnant,” says Dr. Lori Hardy, obstetrician and gynecologist at Northwestern Medicine. “Taking a test earlier than that would possibly give a falsely negative result.” So, when it comes to how soon you should take a pregnancy after sex, the answer “would probably be 10 to 14 days,” Hardy says.
However, you still may not get an accurate answer after that amount of time. Even in that timeframe, there still could be a falsely negative result, since hormone levels in early pregnancy can vary, Hardy explains.
For the most reliable home pregnancy test results, you’ll have to be super patient and wait until the first day of your missed period, according to both OB-GYNs. At that point, Caponero says, most at-home tests are very accurate. “It is so hard to wait — I’m very aware of that,” she says. “But ideally, you wait until you miss your period.”
If you take a test at home and feel like it may not be right, feel free to re-test. “If the initial test is negative, you can retest in 24 to 48 hours,” Hardy says. “If the test remains negative and you miss your period completely, that is the time I’d recommend seeing a doctor.”
Note: Don’t wait until you can take a pregnancy test if you had unprotected sex and you’re not trying to get pregnant, i.e. a condom broke. Emergency contraception pills or an IUD can work from 72 hours to 5 days after sex, so take action quickly.
Are Pregnancy Tests Better at the Doctor’s Office?
If you think going to your doctor’s office will result in more accurate (or quicker) test results, you may be disappointed. “Urine pregnancy tests in the doctor’s office are not necessarily more reliable than sensitive home pregnancy tests,” says Hardy. “A blood test in the doctor’s office would be the most accurate for early pregnancy detection. In most cases, however, with the sensitivity of modern urine pregnancy tests, blood tests are generally not necessary.”
That said, if you have a history of an ectopic pregnancy, Caponero says she would want to follow your blood levels closer since having a pregnancy outside the uterus can be life-threatening.
What’s the Best Time of Day to Take a Pregnancy Test?
Your urine is most concentrated first thing in the morning, so the hormone might be more easily detected in the a.m. in early pregnancy, but you can do a pregnancy test on a sample of urine collected at any time of the day. “Most pregnancy tests are very accurate and are sensitive enough to detect that pregnancy level no matter what time of day the test is taken,” Caponero says.
The Bottom Line
As hard as it may be, your best bet is to wait to take a pregnancy test until after you miss your period. “Some very sensitive pregnancy tests can be used before, from as early as eight days after conception, but hormone levels may vary and the test depends on detecting the hormone level in your urine,” Hardy says. Whether you’re hoping it’s positive or negative, waiting until when you were supposed to have your period will give you the most accurate result.
A version of this story was published May 2019.
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