Pregnancy Test Right After Sex: Will Sperm Affect Results?

It is possible for a small amount of hCG in semen, which is responsible for transporting sperm, to lead to a false positive outcome on a pregnancy test. Nevertheless, this likelihood is low.

However, the chances of this happening are very low because the minuscule amount of hCG that might be mixed with urine when you test is unlikely to impact the result.

The Source for Women claims that a “false-positive test result only happens less than 1% of the time,” and there must be above 25 mIU/mL of hCG for a pregnancy test to produce a positive result, so the odds of sperm affecting the results are quite slim.

How Sperm Can Affect a Pregnancy Test

Maybe you were planning on taking that pregnancy test but got caught in the moment and had sex instead.

Should you go ahead and take the test right after anyway and hope for an accurate result? 

Will Sex Right Before Pregnancy Test Interfere With the Results?

Sex right before a pregnancy test can interfere with the results because of the semen, which contains trace amounts of hCG, left in your body, but the odds of this occurring are very low.

Unless your partner wore a condom and no semen leaked, you could possibly get a false positive result, though this is unlikely.

HCG in Semen

Pregnancy tests look for human chorionic gonadotropin, better known as hCG, to determine pregnancy.

However, there are a few reasons hCG could register on a pregnancy test when you are not pregnant. One of them is semen.

Semen contains a small amount of hCG, so testing right after sex means the test may register the hCG in the semen and give you a positive result but doesn’t necessarily mean you are actually pregnant. 

Remember that the chances of this happening are low, and if you do get a positive result, see your doctor promptly for confirmation.

Should I Wait Before Taking the Test?

There’s not a lot of research on how to avoid false positives on a pregnancy test because they are extremely rare.

It’s best to avoid testing the same day you’ve had sex since there is a small possibility that enough semen will remain to affect the results.

However, this is so rare that it is not a huge cause for concern.

Chances of Pregnancy Test Being Wrong

Most pregnancy tests are 99% accurate. It is extremely rare to get an inaccurate result, but it can happen.

It’s important to know what can affect a pregnancy test to ensure your results are as accurate as possible. 

  • If you test too early, you may not have enough hCG in your system to register that you are pregnant.
  • If you test right after sex, the test may register the hCG in sperm and give you a false positive.
  • If you don’t follow the directions on the test or use an expired test, you can also get inaccurate results.
  • Certain medications can also affect the accuracy of your pregnancy tests, so make sure you know if you are on any of those medications before you try to get a result.
  • Residual hormones from a recent pregnancy loss can lead to inaccurate results.

Causes of a False Positive Pregnancy Test

False positive pregnancy tests are rare.

When they do occur, it’s because hCG has been picked up by the test that is not from a current pregnancy but is from another source.

You can also get a false positive if you don’t follow the directions on the pregnancy test.

Reading a test after it has been left to sit for too long can leave you staring at an evaporation line that looks suspiciously like a positive pregnancy line.

Common issues that cause a false positive pregnancy test are:

  • Severe infections, like UTIs
  • Recent abortion
  • Recent miscarriage
  • Chemical or ectopic pregnancy
  • Recently giving birth
  • Sperm in the body if you have just had sex
  • Certain medication
  • Fertility treatment
  • User error
  • Certain cancers

False Negative Pregnancy Test Causes

It’s rare for a pregnancy test result to be inaccurate, but it can happen. If you get a false negative, it could be due to various reasons.

  • If you test too early, the test may not be able to pick up enough hCG to give a positive result.
  • Using an expired test or not following the directions on a test can cause inaccurate results.
  • The time of day you test may affect the result.
  • Using too much urine on a test can dilute the levels and make it come up negative when you are actually pregnant.
  • Hook effect.

Still questioning if the result of your pregnancy test is accurate?

You can always ask your doctor to draw blood for a result that is not impacted by urine, sperm, or other factors.

A young woman sitting on her couch with a pregnancy test and looking confused.

Can a UTI Cause a False Positive Pregnancy Test?

In very rare cases, a severe urinary tract infection can cause a false positive pregnancy test.

Your body may register more hCG than normal when an infection is severe, and this could lead to a test coming back positive when you are not pregnant.

What Not To Do Before Taking a Pregnancy Test

There are some basic guidelines that could help your pregnancy test results be more accurate. They include knowing what not to do before you test. 

  • Don’t drink a ton of water. Yes, you need to be able to pee for the test, but you don’t want to dilute your urine since that can make it harder for the test to register hCG levels.
  • Don’t have sex right before taking a test because semen can give you a false positive result. This can be devastating when you find out later that you aren’t actually pregnant.
  • Don’t take the test before reading the directions. No matter how intuitive a pregnancy test seems, read the instructions fully before you start the process.
  • Don’t use a pregnancy test that is expired.