What Is Prenatal Testing?

Prenatal testing is a major source of information for your doctor about the well-being of you and your baby. While most testing is routine, some may only be recommended for certain medical and genetic histories. Your provider can discuss benefits and risks, help you decide which tests are right for you, assist in determining priorities, and discuss options.

Routine prenatal testing begins at your first obstetrician appointment. You will receive these tests several times during your pregnancy:

Blood pressure check: High blood pressure may be associated with gestational hypertension, preeclampsia, or other conditions and may require blood pressure medication or dietary changes.

Urine tests: Monthly urine tests alert your doctor to potential gestational diabetes, preeclampsia, and bladder infections.

Blood tests: Blood tests can identify certain infections, like hepatitis B and HIV, your blood type, Rh factor, and anemia.

According to the American Congress of Obstetricians and Gynecologists (ACOG), there are several first trimester tests available.

Ultrasound: An early ultrasound may confirm pregnancy and let you know how far along you are in pregnancy.

Fetal DNA testing: Performed after the ninth week of pregnancy, cell-free fetal DNA screening checks your blood for your baby's DNA to determine if he or she may have certain genetic conditions, like Down syndrome.

Chorionic villus sampling (CVS): CVS is a diagnostic test performed at 10 to 13 weeks of pregnancy that checks the placental tissue to establish if your baby has a genetic condition.

Carrier screening: This test checks your blood to see if you're a carrier of genetic conditions that could affect your baby, like cystic fibrosis, spinal muscular atrophy, and fragile X syndrome.

In your second trimester, your doctor may order certain prenatal tests, says the Office on Women's Health. These include:

Maternal serum screen: Performed at 15 to 20 weeks of pregnancy, this test measures four substances in your blood — alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), estriol, and inhibin A — to determine if your baby may be at risk of certain birth defects.

Amniocentesis: Amniocentesis is usually performed at 15 to 20 weeks of pregnancy, and is more common if you're over the age of 35 or have a family medical history of genetic disorders. A small amount of the amniotic fluid is gathered and evaluated for potential genetic anomalies or disease.

Ultrasound: Usually performed at 16 to 20 weeks of pregnancy, an ultrasound indicates the baby's sex and development, and may also identify any health problems or abnormalities.

Glucose screening: Performed at 24 to 28 weeks of pregnancy, this screening helps identify elevated glucose, which is an indication of gestational diabetes.

In your last trimester, at 36 to 37 weeks of pregnancy, your doctor will test for Group B strep (GSB), an infection you can pass on to your baby during birth. This test checks your cervical fluid to determine if you have GBS.

Prenatal testing is an excellent indicator of the health of you and your baby. It's important to remember that prenatal tests are recommended but are not mandatory. Ask your doctor why certain tests are being ordered, the risks and benefits, and what the results will tell you.

What are the next steps for your pregnancy? Stay on top of your health needs for a happy, smooth birth.

Our maternity teams provide expert care to guide you through the pregnancy, birth and postpartum process. Learn more about mother and baby care at CHI Saint Joseph Health.