What do I need to know about the third prenatal visit?

Throughout your third trimester, you'll be offered more tests depending on your age, health, family medical history, and other things. These can include: Ultrasound: Third-trimester ultrasounds can examine the placenta, and sometimes are part of a test called a biophysical profile (BPP) to see whether the baby is getting enough oxygen. Women with high-risk pregnancies may have multiple ultrasounds in their third trimester. Glucose screening: This test checks for gestational diabetes, a short-term form of diabetes that develops in some women during pregnancy and can cause health problems for the baby, especially if it is not diagnosed or treated. You'll drink a sugary liquid, then have a blood test an hour later to check glucose levels. Group B strep test: Between your 35th and 37th weeks of pregnancy, the doctor will check you for group B streptococcus (GBS) infection. GBS bacteria are found naturally in the vaginas of many women but can cause serious infections in newborns. This test involves swabbing the vagina and rectum. A woman whose test comes back positive must go to the hospital as soon as labor begins so that intravenous (IV) antibiotics can be started to help protect the baby from becoming infected. Nonstress test: A nonstress test (NST) is usually done when a health care provider wants to check on the health of the fetus, such as in a high-risk pregnancy or when the due date has passed. The test checks to see if the baby responds normally to stimulation and is getting enough oxygen. A baby that doesn't respond isn't necessarily in danger, but more testing might be needed. Contraction stress test: This test stimulates the uterus with pitocin, a synthetic form of oxytocin (a hormone secreted during childbirth), to determine the effect of contractions on fetal heart rate. It may be recommended when an earlier test indicated a problem and can see whether the baby's heart rate is stable during contractions. Remember that tests are offered to you — it's your choice whether to have them. To decide which tests are right for you, talk with your doctor about why a test is recommended, its risks and benefits, and what the results can — and can't — tell you.