If you take a pregnancy test too early, your results may be inaccurate. Pregnancy tests detect a hormone called HCG, which your body produces when a fertilized egg implants in the uterus.
Though today’s home pregnancy tests can detect traces of hCG in your urine much earlier than before, a false negative can still occur if you take the test too soon.
Ovulation
If you’re on a predictable 28-day menstrual cycle and ovulate regularly, you can get accurate pregnancy test results about two weeks after unprotected sex. The reason is that your body needs time to build up hCG, the hormone detected by at-home pregnancy tests. Taking the test too early can result in a negative result, which is frustrating, especially after you’ve been hoping to become a parent.
Most at-home pregnancy tests are sensitive enough to detect hCG in your urine by the time your period is due. The only exception is if you have an irregular menstrual cycle. In that case, you may be able to take the test from the day after your expected period begins.
Another sign of ovulation is implantation bleeding, which resembles a light spotting or period. It’s typically one to two days long and can consist of a few drops of blood or light pink to brown discharge.
If you’re concerned about implantation bleeding, talk to your doctor. She or he may suggest getting a blood pregnancy test, which is more precise than a urine test and can detect hCG up to a week before you miss your period. Blood tests are expensive, however. And they’re only available through your healthcare provider, not at a pharmacy or grocery store.
Implantation
When the sperm and egg join to form a fertilized embryo, it attaches to the lining of your uterus. This process is called implantation and can trigger light bleeding, which looks more like spotting than a period. Implantation typically happens around six days after you ovulated, but it can occur sooner or later.
Once the fertilized embryo implants, it begins to produce a pregnancy hormone called human chorionic gonadotropin or hCG. This is what pregnancy tests detect to tell if you’re preggers. It can take anywhere from a few days to a couple of weeks for the hCG levels in your body to reach a high enough level for a test to be able to read, depending on the type of pregnancy test you’re using.
This is why experts recommend waiting to take a test until you miss your period. This also gives the hCG in your body time to build up, so you’ll get the most accurate results possible. However, some tests are more sensitive than others and can detect hCG earlier. If you’re worried about an unwanted pregnancy or have a late period, there are options for emergency contraception that can help you avoid a miscarriage. You can also use the “morning-after pill,” which can be used up to five days after unprotected sex to prevent pregnancy.
Symptoms
It’s important to know if you’re pregnant as soon as possible, especially after unprotected sex or when contraception fails. However, it’s also important to remember that it is possible to get a false positive or negative test result if you take a pregnancy test too early or too late.
The best time to take a pregnancy test is on the first day of your missed period. It’s also a good idea to test when you think you’re ovulating, as conception occurs shortly after ovulation. Some tests can detect pregnancy hormones in the urine even up to 6 days before your period is due. But these tests are less reliable and may show a negative result, because the HCG levels are too low.
The earliest symptoms of pregnancy include spotting or bleeding, which is caused by the fertilized egg attaching to the wall of your uterus. This is called implantation and can occur anywhere from six to 12 days after the egg has been fertilized. If you’re worried that you might be pregnant, it’s best to see a doctor as soon as possible. Your GP or sexual health clinic will be able to perform a pregnancy test, and they can provide information on your options and next steps if you are pregnant. Some community clinics and Planned Parenthood centers offer low-cost pregnancy testing.
Tests
It’s important to take a home pregnancy test at least once on the day after you think you may have missed your period. It takes a while for sperm to fertilize an egg, and the body to produce enough of the hormone that can be detected by a home test. This is especially true if you’ve had unprotected sex (which doesn’t just mean bareback penis-in-vagina intercourse—it can also mean sex that involved a broken condom or expired one).
The most accurate way to check for pregnancy is on the first day of your missed period, although some extra-sensitive tests can be used even before then. You can also get a blood test, which is more accurate than a urine one but takes longer to receive results. If you want to know ASAP, many Planned Parenthood and community clinics have sliding-scale testing centers where you can get a test for a little less than what it costs at the drugstore.
It’s also a good idea to get tested for sexually transmitted diseases. However, the window of time that is considered safe to do this can vary from disease to disease. Read our primer on STD incubation periods for all the details, including how long after sex you should wait to test for chlamydia, gonorrhea, and HIV. Plus, learn which symptoms are the earliest signs of a STI and what you can do to prevent STIs from spreading.
