Screening for Down Syndrome: Why, When, and How

Abstract

Once, expectant parents didn't know of the health or sex of their babies before birth. Now, pregnant women routinely are asked if they want to know the sex of the fetus (developing baby) and are offered antenatal (before birth) screening tests for certain birth defects. Additional screening — as well as genetic counseling — is also offered to some women before or during pregnancy based on personal and family health histories. The American College of Obstetricians and Gynecologists recommends that all pregnant women be informed about screening for the most common detectable birth defect, Down syndrome. About Birth Defects and Screening Tests Birth defects are physical, mental, or biochemical abnormalities that are present at birth. Down syndrome — a genetic disorder that causes mental retardation, developmental delays, and physical disorders — is one example. Many pregnant women opt for screening tests to detect possible problems. Ultrasound imaging can provide clues to some physical defects in the fetus, such as heart problems, neural tube defects (for example, spina bifida, in which the baby's spine does not develop completely), and abdominal wall defects (when the abdominal organs are not in their proper places). …