Reducing birth defect risk in advanced maternal age.

The incidence of birth defects increases with maternal age. Recent advances in fetal diagnosis, coupled with elective abortion, offer the older pregnant woman an opportunity to reduce this risk. To determine the magnitude of potential risk reduction, we reviewed the maternal age-specific incidence of infants born with one or more severe birth defects in metropolitan Atlanta from 1968 to 1975, removing from analysis certain anomalies that were preventable by currently available methods. For women aged 35 to 44 years, the risk of bearing an infant with a severe birth defect was reduced to a level comparable with that for younger women. Despite prenatal diagnosis and elective abortion, the risk for women aged 45 years or older, although reduced considerably, was two times greater than that for women aged 34 years or younger.