Prenatal Testing: Learn More About the Health of Your Baby

Prenatal testing provides important information as to the health and development of a baby in the months before he or she is born. Many of these tests have become a routine part of a regular pregnancy, while some are performed only at the request of the parents or the doctor. Though not all conditions are detectable through prenatal testing, many are—particularly through birth defects testing and genetic testing. Results can help parents prepare for any special care or health needs their baby may need after birth.

Routine Prenatal Testing

Routine prenatal testing includes blood and urine tests that check for the following potential problems:

• Anemia, which could increase your risk of preterm delivery
• Antibodies that show if you’re immune to rubella or chickenpox, both of which can cause birth defects if the mother is infected during pregnancy
• Bacteria, which can indicate an infection
• Blood type, including whether or not you carry a protein called the Rh factor—the lack of which can indicate a mother needs treatment to protect the baby from a potential blood problem
• Glucose, which can be a sign of diabetes
• Protein, which can signal a urinary tract infection or preeclampsia
• Sexually transmitted diseases

Blood and urine tests are typically performed once or more during pregnancy to help monitor the health of mother and baby. An ultrasound is also an optional routine test that shows a picture of the baby on the screen and can be used to confirm a heartbeat, determine gestational age, confirm multiples in pregnancy, verify dates and growth, and detect gender and some possible birth defects.

A glucose challenge screening (blood test) may also be performed between 26-28 weeks to determine a woman’s risk of gestational diabetes (diabetes brought on by pregnancy). A positive result indicates the need for a Glucose Tolerance Test, which can further determine a diagnosis.

Birth Defects Testing

In addition to routine prenatal testing, parents may also choose birth defects testing to help determine the health of their babies. Though these tests do not help in preventing birth defects, they do provide additional information that can help parents prepare for possible treatments their babies may need after birth. Birth defects testing includes the following options:

• First trimester screening, which uses blood tests and an ultrasound to assess the risk of Down syndrome and trisomy 18.
• Second trimester screening, which again uses blood tests to screen for Down syndrome, trisomy 18, and neural tube birth defects, and may also detect spinal cord and abdominal wall defects.
• Chorionic villus sampling (CVS), in which the doctor looks at cells form the placenta to detect Down syndrome, sickle cell disease or cystic fibrosis.
• Amniocentesis, in which the doctor takes a sample of the amniotic fluid to detect neural tube birth defects.
• Ultrasounds performed later in pregnancy can help detect Down syndrome, or developmental problems in the heart, spine, belly, or other areas.

Genetics Testing

Genetics testing may overlap with birth defects testing, as it uses similar types of tests, but is looking specifically for genetic disorders, like Down syndrome. Genetic testing during pregnancy can also help diagnose Duchenne muscular dystrophy, hemophilia A, sickle cell anemia, polycystic kidney disease, and Tay Sachs disease.

Parents can also elect to undergo genetic screening before pregnancy, which can detect defective genes that raise the risk of certain types of genetic disorders like cystic fibrosis, sickle cell disease, Tay Sachs disease, familial dysautonomia, thalassemia (blood disorder), and Fragile X syndrome.

Late-Pregnancy Testing

Certain types of prenatal testing may be performed late in the pregnancy to ensure the well-being of the fetus. These include:

• Biophysical profile testing, which is usually done between 38-42 weeks, and includes an ultrasound and the measurement of amniotic fluid, as well as a non-stress test (details below). The test looks at muscle tone, body movements, breathing movements, amniotic fluid levels, and heart rate. A score of 2 in each of these areas is normal. Lower scores may encourage a doctor to induce labor or perform a cesarean section.
• Non-stress testing monitors the baby’s heart rate in conjunction with uterine activity. Doctors are looking for responsiveness from the baby.
• Stress testing checks to see how the baby will respond to the stress of contractions during labor. The mother is given an injection to induce contractions and the baby is monitored for reaction. If the baby doesn’t appear okay, the doctor may elect to induce labor or perform a cesarean.

All prenatal testing is best discussed with your doctor. He or she may recommend certain tests depending upon your health and medical history, but the decision is always yours. You can also talk to a genetic counselor or other healthcare provider about the pros and cons of certain types of prenatal testing, such as birth defects testing.