Maternal serum alpha-fetoprotein screening: benefits, risks, and costs.

Based upon previously published reports, the benefits and risks of screening a hypothetical population of 10,000 women are analyzed, and the cost benefit of maternal serum alpha-fetoprotein screening is reviewed. Five hundred women would have an initially elevated serum alpha-fetoprotein and experience moderately severe anxiety until further tests are completed. One hundred fifty pregnancies would undergo amniocentesis with approximately one spontaneous abortion resulting from the procedure. Fifty sets of twins, 86 pregnancies with underestimated gestational age, and 50 pregnancies at risk for low birthweight or fetal death would be identified. All four anencephalics and three of four fetuses with spina bifida would be detected. The benefits to pregnant women of prenatal screening for neural tube defects exceed the risks. At the present incidence of neural tube defects, the cost of prenatal screening to society approximately equals the economic savings. If the incidence of neural tube defects continues to fall, the benefits, risks, and costs will have to be reevaluated. There are insufficient data to determine adequately the benefits, risks, and costs of the screening for Down's syndrome with maternal serum alpha-fetoprotein, and such screening should be discouraged.