Tests During Pregnancy

Whether your pregnancy is progressing normally or if concerns are present, your obstetrician may recommend some of the following tests.

• An ultrasound exam is a safe procedure and one of the most common tests given to pregnant women. It monitors your fetus’s growth and the well-being of his internal organs by taking sonograms (images made from sound waves) of him. It can ensure that your baby is developing normally and will help determine any problems or fetal abnormality. It also can be used if your doctor suspects that your baby is in the breech position. Although most babies are in a head-down position in the uterus at the time of delivery, breech babies are positioned so that their buttocks or feet will move first through the birth canal, before the baby’s head. Although some breech babies can safely be delivered vaginally, the risk of complications may be higher in many breech deliveries, and thus your doctor may recommend delivery by Cesarean section.
• A nonstress test electronically monitors the fetus’s heart rate and movements. In this test, a belt is positioned around your abdomen. It is called a “nonstress” test because medications are not used to stimulate movement in your unborn baby or trigger contractions of the uterus.
• A contraction stress test is another means of checking the fetus’s heart rate, but this time it is measured and recorded in response to mild contractions of the uterus that are induced during the test. For example, an infusion of the hormone oxytocin may be used to cause these contractions. By monitoring your baby’s heart rate during the contractions, your doctor may be able to determine how your baby will react to contractions during the actual delivery; if your baby is not responding favorably during these contractions, the delivery of your baby (perhaps by Cesarean section) might be scheduled prior to your due date.
• A biophysical profile uses both a nonstress test plus an ultrasound. It evaluates the movement and breathing of the unborn baby, as well as the volume of amniotic fluid. Scores are given for each component of the profile, and the collective score will help determine whether there is a need for an early delivery.

Other tests may be recommended, depending on your own physical health and personal and family history. For example, particularly for women with a family history of genetic problems or for those who are age thirty-five or older, your obstetrician may advise tests that can detect genetic disorders. The most common genetic tests are amniocentesis and chorionic villus sampling.

Your doctor may recommend other screening tests. For example:

• Glucose screening can check for high blood sugar levels, which could be an indication of gestational diabetes, a form of diabetes that can develop during pregnancy. To conduct the test, which is usually performed between the twenty-fourth and twenty-eighth week of pregnancy, you’ll be asked to drink a sugar solution and then a sample of your blood will be collected. If a high level of glucose (a type of sugar used for energy) is in the blood, then additional testing should be done. This will determine if you do have gestational diabetes, which is associated with an increased likelihood of pregnancy complications.
• Group B streptococcus (GBS) screening, which will determine whether a type of bacteria is present that can cause a serious infection (such as meningitis or a blood infection) in your baby. While GBS bacteria are common and may be found in the mother’s vagina or rectum—and are harmless in healthy adults—they can cause illness if they’re passed to a newborn during childbirth. If GBS is detected in a pregnant woman, the doctor will prescribe antibiotics to be given through a vein (intravenously) during the birthing process; once the baby is born, she may be observed for a longer time in the hospital nursery. The GBS screening test is usually given between the thirty-fifth and thirty-seventh week of pregnancy.
• HIV (or human immunodeficiency virus) testing is now commonly done in pregnant women, preferably early in their pregnancy. HIV is the virus that causes AIDS, and when a pregnant woman is infected with the virus, it can be passed to her baby during pregnancy, delivery of her baby, or during breastfeeding.