Prenatal test that tests for birth defects.

The Alpha Fetoprotein (AFP) Test is a commonly used prenatal test to monitor the level of AFP—a possible indicator of developmental abnormalities—in the liver of a fetus during high-risk pregnancies. The protein is obtained either through amniotic fluid extracted during an amniocentesis or from a sample of the mother's blood, usually collected at about the sixteenth week of pregnancy. High AFP levels may indicate abnormal development of the brain or spinal cord or problems with the abdominal wall. Elevated levels of AFP are also an indicator of premature delivery and low birth weight. Low levels of AFP can point to chromosomal disorders, including Down syndrome. AFP screening is problematical because of the high rate of false positives (over 90% of abnormal readings), creating unnecessary anxiety and necessitating further tests. It is generally recommended that women have two AFP screenings and an ultrasound to arrive at a definitive result. The test is usually indicated only for women with a family history of neural tube defects such as spina bifida or other problems.

For Further Study

Books

Blatt, Robin J. R. Prenatal Tests: What They Are, Their Benefits and Risks. New York: Vintage Books, 1988.

Charlish, Anne, and Linda Hughey Holt. Birth-Tech: Tests and Technology in Pregnancy and Birth. New York: Facts on File, 1991.

Morrison, George S. The World of Child Development: Conception to Adolescence. Albany, NY: Delmar Publishers, 1990.