Prenatal Screenings: Spot Health Risks Before Birth

During pregnancy, ob-gyns use routine lab and diagnostic tests to help monitor the health of women and their babies, identify problems, and develop treatment plans. Most women will receive these common screenings as part of their prenatal care:

  • Blood glucose tests screen for the amount of sugar (glucose) in the bloodstream. High levels can signal diabetes. Unchecked diabetes can lead to liver damage, birth defects, stillbirth, and other complications for mother and baby.
  • Blood type and antibody testing determines a woman’s blood group (A, B, AB, or O) and Rh type (positive or negative). Fetal problems may occur when an Rh negative woman carries a fetus that is Rh positive.
  • Screening for birth defects (such as Down Syndrome) may be performed in the first and/or second trimester.
  • Late in pregnancy, women are tested for group B streptococcus (GBS) bacteria, which can cause infections of the blood, lungs, brain, or spinal cord in infants. GBS can be transmitted from an infected mother to the baby during delivery.
  • Hemacrit and hemoglobin tests check the blood for low iron levels (anemia).
  • HBV testing screens for Hepatitis B, a virus that affects the liver and can cause severe complications in newborns if passed from mother to baby.
  • All pregnant women should be screened for HIV infection—a disease that attacks the body’s immune system. Treatment of HIV-positive mothers during pregnancy can drastically reduce the risk that the infants will become infected and help improve the mother’s health.
  • A blood test is used to check for signs of past rubella (German measles) infection. Pregnant women who have not had or not been vaccinated against rubella should avoid any infected individuals and be vaccinated after delivery.
  • Screening for sexually transmitted diseases, such as chlamydia, gonorrhea, and syphilis, may be recommended. They can cause preterm birth, miscarriage, eye infections, birth defects, or other problems.
  • At each prenatal visit, urine analysis checks for elevated blood sugar and protein levels and signs of bladder and kidney infections.

Depending on a woman’s age, health history, or ethnic background, additional screenings may be offered for genetic disorders and birth defects, such as cystic fibrosis or spina bifida. Learn more about prenatal screenings on ACOG’s website.