A nonstress test is a third-trimester test that monitors the baby's movements. The test is done in a health-care provider's office. A belt is attached around the mother's belly for about half an hour to monitor uterine contractions and the baby's heart rate.
The baby's heart rate in response to movements she makes is monitored to determine if the baby is getting enough oxygen and to make sure the nervous system is responding. The test is said to be reactive if the baby's heart rate accelerated with movement and nonreactive if not. A nonreactive test may indicate a fetal sleep cycle rather than a problem. If the baby is asleep, a noise (acoustic stimulator) may be used to wake her up. Nonstress tests are ordered when there is a concern about fetal movement or if the pregnancy is high risk. Some practitioners routinely perform nonstress testing in the third trimester in women 35 or older. If the result is still nonreactive, a biophysical profile is recommended to study the baby's behavior by ultrasound.
Between your thirty-fifth and thirty-seventh week of pregnancy, your health-care provider will do an internal exam and take a swab from the vagina and rectum to be tested for group B strep (GBS). 30 percent of women carry this bacteria, which can be passed to the baby during delivery and cause serious problems. If GBS is detected, you'll be given IV antibiotics during labor.