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The complete guide to third trimester pregnancy tests

Here we are in the third trimester of your pregnancy journey. You've come a long way with baby. So when it comes to prenatal tests, you may think you pretty much know the drill. But there are just a few more tests that you still need in the weeks ahead.

Your final exams

Wondering what tests you can expect? Some tests are recommended for all women. Others may be suggested based on any risk factors you have.

During your checkups, you and your provider can decide which tests are right for you. Here are some prenatal tests that may be recommended:

Urine tests. You'll continue to have these at each of your prenatal care visits to screen for problems like urinary tract infections and pre-eclampsia (high blood pressure).

Group B streptococcus (GBS). This test is routinely done between 35 and 37 weeks. It checks for bacteria that probably won't hurt you but that can harm your newborn baby. GBS normally lives in your body. You can pass it to your baby during birth. In babies, GBS can cause serious infections, like pneumonia (a lung infection) or meningitis (infection around the brain).

To test you for GBS, a small sample of cells are collected from the vagina and rectum and sent to a lab for analysis. Results should be ready in a few days. Until then, try not to worry! If you do have GBS, your provider can give you antibiotics during labor to help prevent the infection from passing to your baby.

Tests for STIs (again)

Even if you've already had them, your prenatal provider may want to repeat certain tests to check for sexually transmitted infections (STIs), such as:

  • Human immunodeficiency virus (HIV), the virus that causes AIDs. 
  • Syphilis.
  • Chlamydia.
  • Gonorrhea.

Other tests

During the third trimester, some women may need other tests to check on their baby's health—for instance, if there is an increased risk of health problems. According to the American College of Obstetricians and Gynecologists, these tests may include:

Nonstress test. Performed after 28 weeks, this test records fetal heart rate and response times and looks for signs of fetal distress, such as lack of oxygen. It involves using a special belt around your belly to measure your baby's heart rate.

Biophysical profile. This test involves the nonstress test and an ultrasound to monitor the overall health of the baby. It can sometimes help determine if a baby should be delivered early.

More pregnancy news

There's another test your doctor may ask you to complete at home. Learn what a kick count is and how to do one on your own.

Reviewed 1/23/2023

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