No, pregnancy will not show up on an STD test. The two types of tests look for completely different things in your body, and there is no overlap between them. An STD test cannot detect pregnancy, and a pregnancy test cannot detect an STD.
Why STD Tests Can’t Detect Pregnancy
Pregnancy tests work by detecting a single hormone called human chorionic gonadotropin (hCG), which is produced by the placenta after a fertilized egg implants. This hormone exists in your blood and urine only during pregnancy, and it has nothing to do with sexually transmitted infections.
STD tests, on the other hand, search for specific pathogens or your immune system’s response to them. Chlamydia and gonorrhea screening uses a method called nucleic acid amplification testing (NAAT), which identifies the genetic material of bacteria in a urine or swab sample. HIV screening detects viral antigens and antibodies your body produces in response to the virus. Syphilis testing looks for a different set of antibodies. Hepatitis B and C tests target surface antigens or antibodies unique to those viruses. None of these tests measure hCG or any pregnancy-related marker.
Both Tests Can Use Urine, but Differently
Part of the confusion may come from the fact that both pregnancy tests and some STD tests use a urine sample. But the lab processes that urine in entirely different ways depending on which test was ordered. A pregnancy test scans for hCG. A chlamydia or gonorrhea NAAT scans for bacterial DNA. Providing a urine sample for STD screening will not accidentally reveal a pregnancy, because the lab isn’t running a pregnancy test on that sample unless one was specifically requested.
In clinical settings, leftover urine from a pregnancy test is sometimes reused for STI screening, or vice versa, but only when a provider has ordered both tests separately. The sample collection might happen at the same time, but the tests themselves remain distinct.
Pregnancy Can Cause a False Positive on Syphilis Tests
There is one indirect way pregnancy can affect STD test results, though it won’t reveal that you’re pregnant. Pregnancy is a known cause of false-positive results on syphilis screening tests. Both the initial screening test and the confirmatory test can occasionally produce a reactive result in a pregnant person who does not actually have syphilis. This happens because pregnancy-related changes to the immune system can alter how certain antibody tests behave. Autoimmune conditions, recent vaccinations, and acute viral infections can cause the same issue.
If you’re pregnant and receive a positive syphilis result, your provider will typically run additional testing to determine whether the result reflects an actual infection or a false positive caused by pregnancy-related immune shifts.
Why STD Testing Matters During Pregnancy
Even though STD tests won’t tell you whether you’re pregnant, they become especially important once you know you are. The CDC recommends that all pregnant people be screened for syphilis, HIV, hepatitis B, and hepatitis C at the first prenatal visit. Screening for chlamydia and gonorrhea is recommended for all pregnant people under 25, and for older pregnant people with risk factors.
The reason for this broad screening is that most STIs produce no noticeable symptoms. You or a partner could be positive without knowing it. During pregnancy, untreated infections carry serious risks for both the mother and the baby. Chlamydia has been linked to increased risk of preterm birth, stillbirth, and low birth weight. One study found that chlamydia increased mother-to-child HIV transmission by nearly 50%. Gonorrhea is associated with preterm birth, low birth weight, and neonatal eye infections. Trichomoniasis raises the risk of preterm birth by about 41% and increases the chance of delivering a baby that is small for gestational age by 51%.
The good news is that many of these infections are curable with treatment during pregnancy, which is why early screening is standard practice.
If You Need Both Tests, Ask for Both
If you’re trying to find out whether you’re pregnant and also want to check your STI status, you’ll need to request both types of testing. Some clinics and prenatal providers will bundle these together at your first visit, running pregnancy confirmation alongside the standard STI panel. But this only happens when both tests are explicitly ordered.
At-home options exist for each type of test separately. Home pregnancy tests are widely available over the counter and detect hCG in urine. At-home STI kits, which typically test for chlamydia, gonorrhea, and sometimes HIV or syphilis, require you to mail a sample to a lab. These are separate products that test for separate things, and no single at-home kit screens for both pregnancy and STIs simultaneously.