Demystifying Prenatal Screening

During pregnancy, prenatal screenings can determine whether a baby is at risk for health or developmental issues. If a screening identifies a potential problem during birth, a health care provider can learn more by performing a diagnostic screening.

Here are the most common prenatal screenings:

Blood tests: Routine blood tests check for whether an expectant mother is immunized against rubella; check for hepatitis B, syphilis, and HIV; and determine blood type and Rh factor, which may impact pregnancy. Other blood tests check for certain proteins and hormones which can indicate possible chromosomal abnormality and glucose – both signs of gestational diabetes. Throughout pregnancy, blood tests can provide information on the overall health of mother and fetus.

Ultrasound: An ultrasound uses sound waves to create an image of a fetus in the uterus. This can provide information on fetus size and position as well as the development of bones and organs. Between the 11th and 14th weeks of pregnancy, a special ultrasound checks for accumulation of fluid at the back of the neck, which can indicate greater risk for Down Syndrome.

Chorionic villus sampling: Typically performed between the 10th and 12th weeks, this screening tests a small piece of tissue from the placenta for genetic abnormalities like Down syndrome and birth defects. There are two types – transabdominal or transcervical tests. The test may cause spotting, cramping, and in very rare cases, miscarriage.

Amniocentesis: Amniotic fluid containing fetal cells and chemicals surrounds the fetus during pregnancy. Amniocentesis involves removing a small amount of this fluid for testing, which provides information about genetic abnormalities, fetal maturity, and other issues. Amniocentesis can be performed around the 15th week of pregnancy and beyond.

Group B Strep Screening: The bacteria of Group B Streptococcus (GBS) can cause serious infections in pregnant women and newborns. Health care practitioners can treat this infection with antibiotics to prevent its spread to newborns.

While all prenatal screening tests provide information, some are routine, while others some may require more complex decisions. If you have questions or concerns, speak to your health care provider about the risks and benefits of prenatal screening.