During prenatal check ups throughout a pregnancy, a woman will undergo numerous tests to promote a healthy pregnancy and delivery. These tests are helpful in reducing or identifying the risks of complications, like urinary tract infections, sexually transmitted diseases in the mother and poor growth and development of the fetus. Depending on the results of earlier tests, a woman may have only a few necessary evaluations in the third trimester.
Biophysical Profile
A biophysical profile (BPP) consists of the use of an ultrasound and a nonstress test (NST) to analyze fetal health, explains the American Pregnancy Association. Typically, this test is only performed when earlier evaluations revealed a cause for concern over the infant's development. The ultrasound component of the BPP is no different from a routine examination that allows the health care provider to view the infant in the womb. The NST consists of a monitor that is placed on the mother's abdomen to chart the baby's movement and heart rate over the course of 20 to 30 minutes. The results of this test can identify normal or abnormal breathing, movement, muscle tone, heart rate or amniotic fluid levels. The findings of this test can indicate a need for the baby to be delivered sooner, such as via Cesarean section or induction. The NST and ultrasound can be used independently throughout the pregnancy to reassure the mother and the health care provider that the baby is still doing well before delivery.
Glucose Challenge Screening
Between the 26th and 28th weeks of pregnancy, a woman is given a glucose challenge screening to rule out gestational diabetes--diabetes that only occurs during pregnancy. Gestational diabetes can pose risks to the mother and the baby due to poor glucose management. A positive result on the glucose challenge screening will lead the mother to be given the glucose challenge screening in the third trimester, explains the American Pregnancy Association. A few days before the test, the woman will need to eat at least 150 mg of carbohydrates. She then fasts for 14 hours before the test. During the test, the woman's blood is drawn to identify her fasting blood glucose level, explains the American Pregnancy Association. Following this, she is given a larger volume of a glucose drink and her blood is drawn every hour for three hours.
Urine Analysis
It is common for a woman to have her urine tested at every prenatal appointment. This test consists of her providing a clean, midstream sample of urine. The sample will be analyzed for the presence of blood, kidney or urinary tract infection, sugars, proteins, ketones and bacteria, says the American Pregnancy Association. A number of health concerns can be identified with this test, including diabetes and preeclampsia (high blood pressure).
Group B Strep Infection
Group B streptococcus (GBS) is a bacterial infection often found in the vaginal or rectal areas. During the third trimester a woman will have these areas wiped with a sterile swab and the specimen will be evaluated for the presence of the bacteria, explains the Mayo Clinic. GBS normally occurs in the digestive tract, but when test results reveal its presence in the vagina or rectal areas, the woman will be treated with antibiotics during delivery to prevent transmission to her baby. Intravenous antibiotics are very successful in preventing the transmission of the infection from the mother to the baby. When a woman goes into labor on or before the 37th week or the rupture of the membrane (waters) occurs 18 or more hours before delivery, the risk of the baby being infected with GBS is higher because the mother is not as likely to receive antibiotic treatment to kill the bacteria before the baby is delivered.
Other Evaluations
During the third trimester a woman may undergo a series of evaluations with her health care provider. These are not tests necessarily, but they help prepare for delivery. BabyCenter.com indicates such evaluations may include the fundal height, cervical changes and the baby's position. The fundal height is the distance from the pubic bone to the edge of the uterus, which indicates the growth of the baby and uterus. Evaluating the cervical changes allows the health care provider to determine if the cervix thinning and dilating in preparation for labor. Understanding the baby's position at this stage in labor can help the mother and the health care provider make decisions about the upcoming labor. A baby who is breech (feet down) may be better delivered via cesarean section. In some cases, the doctor will attempt to move the baby by carrying out a procedure called a version.
