In the last three months of pregnancy, your baby is packing on the pounds, growing finger- and toenails, and opening and closing their eyes. You’re likely feeling pretty tired and might find yourself short of breath. This is completely normal. You should also be feeling more movement from baby.

By week 37, your baby can be born and considered early-term. The longer they stay put, the healthier they’ll be at birth.

If your pregnancy is healthy and low-risk, you should be attending prenatal appointments every two to four weeks up until 36 weeks. Then it will be time for weekly checkups until you deliver.

At your appointments, your doctor will weigh you and check your blood pressure. Your doctor may ask you to provide a urine sample, which they’ll use to check for infection, protein, or sugar. The presence of protein in the urine in the third trimester can be a sign of preeclampsia. Sugar in urine could indicate gestational diabetes.

Your doctor will measure your belly to check the baby’s growth. They may check your cervix for dilation. They might also give you a blood test to check for anemia, especially if you were anemic earlier in your pregnancy. This condition means you don’t have enough healthy red blood cells.


You may get ultrasounds, just as you have in previous weeks, to confirm the baby’s position, growth, and health. Electronic fetal heart rate monitoring checks to make sure the baby’s heart is beating properly. You’ve likely had some of these tests by now.

Group B Streptococcus Screening

Many of us carry group B strep bacteria in our bowel, rectum, bladder, vagina, or throat. It usually doesn’t cause a problem for adults, but it can cause serious and potentially fatal infections in newborns. Your doctor will test you for group B strep in weeks 36 to 37 to make sure your baby isn’t exposed to it.

They’ll swab your vagina and rectum, and then examine the swabs for the bacteria. If the test is positive for bacteria, they’ll give you antibiotics before delivery so your baby isn’t exposed to group B strep.

STI Tests

During the third trimester, your doctor might also check for sexually transmitted infections (STIs). Depending on your risk factors, your doctor might test for:

  • chlamydia
  • HIV
  • syphilis
  • gonorrhea

These could infect your baby during delivery.

Your doctor may perform other tests if they suspect your baby is at risk for certain conditions or isn’t developing as expected.


You may receive an amniocentesis if your doctor thinks your baby might have a bacteria infection called chorioamnionitis. They may also use the test if they’re concerned about fetal anemia. This test is often done during the second trimester to detect chromosomal issues like Down syndrome. It’s also used to test for fetal lung function.

During amniocentesis, your doctor will insert a long, thin needle through your abdomen into your uterus. They’ll withdraw a sample of amniotic fluid. They’ll consult an ultrasound to determine the exact location of your baby so the needle doesn’t touch them.

A small risk of miscarriage or premature delivery is associated with amniocentesis. It’s possible your doctor will recommend inducing delivery if they discover an infection during the procedure. This will help treat the infection as soon as possible.

The Nonstress Test

The nonstress test (NST) measures your baby’s heart rate as they move around. It may be ordered if your baby isn’t moving normally or if you’re past your due date. It can also detect if the placenta is healthy.

Unlike stress tests for adults, which purposefully stress the heart to monitor its function, the NST just involves placing a fetal monitor over your baby bump for 20 to 30 minutes. Your doctor may perform the NST weekly if you have a high-risk pregnancy, or anytime beginning around the 30th week.

Sometimes the heart rate is slow because your baby is dozing. In this case, your doctor might try to gently wake them. If the heart rate remains slow, your doctor may order a biophysical profile. This combines the NST information with an ultrasound exam to get a better understanding of the baby’s condition.

Contraction Stress Test or Oxytocin Challenge

The contraction stress test also measures fetal heart rate, but this time — you guessed it — with some stress. Not much stress, though. It will be just enough stimulation of your nipples or just enough oxytocin (Pitocin) to stimulate mild contractions. The goal is to see how the baby’s heart responds to contractions.

If all is normal, the heart rate will remain stable even when contractions restrict blood flow to the placenta. If the heart rate is unstable, your doctor will have a much better idea of how the baby will react once delivery begins. This will help them take proper measures at that time, such as speeding up delivery or doing a cesarean delivery.

You might feel more anxious about your baby’s health as your due date approaches. That’s normal. Don’t hesitate to contact your doctor with any questions or concerns. Your anxiety affects the baby, so it’s best to put yourself at ease.