Whether your pregnancy is progressing normally or if there are concerns, your obstetrician may recommend some of the following tests.
This safe and common test monitors your baby's growth and the well-being of their internal organs by taking sonograms (images made from sound waves). It can ensure your baby is developing normally and will check for any physical abnormalities. It also can be used close to the time of delivery if your doctor suspects your baby is in the breech position (positioned so that his buttocks or feet would move first through the birth canal, before the baby's head). Because of the risk of head entrapment, breech deliveries are not advised in developed countries such as the United States except in very rare circumstances. Even when a new mother is fully dilated, if the baby is found to be breech, the latest recommendations are to always perform a C-section.
Nuchal translucency scan
A nuchal translucency scan is an ultrasound performed at 11–12 weeks to look for signs of genetic abnormalities like Trisomy 13, Trisomy 18, and Trisomy 21 (Down syndrome). This test is often combined with two blood tests, PAPP-A and beta-HCG, to create a risk score called the First Trimester Combined Test or "triple test." In the second trimester the obstetrician may check a dimeric inhibin A (DIA) level, combining it with the triple test to produce a "quad test."
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 no medications are used to stimulate movement in your unborn baby or trigger contractions of the uterus.
Contraction stress test
A contraction stress test is another means of checking the fetus's heart rate, but in this case it is measured in response to mild contractions of the uterus that are stimulated (for example, by an infusion of the hormone oxytocin). 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 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 and an ultrasound. It evaluates the movement and breathing of the unborn baby, as well as the volume of amniotic fluid. A collective score will help determine whether there is a need for an early delivery.
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. To conduct the test, usually performed between the twenty-fourth and twenty-eighth week of pregnancy, you'll be asked to drink a sugar solution before a blood sample is collected. If a high level of glucose 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. This is usually a urine sample. 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 transmitted during childbirth. If GBS is detected in a pregnant woman, antibiotics to be given intravenously during the birthing process; once the baby is born, they may be observed for a longer time in the hospital nursery. The GBS screening test is usually performed 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, or during breastfeeding. Early diagnosis and treatment can decrease the risk of infection in the baby. It is important to know a pregnant woman's HIV status so that appropriate medications can be given during pregnancy and labor. Babies born to HIV-positive mothers also receive preventive medications after 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 35 or older, your obstetrician may advise tests that can
detect genetic disorders. The most common genetic tests are amniocentesis and chorionic villus sampling.