The incidence of birth defects increases with maternal age. Recent advances in fetal diagnosis, coupled with elective abortion, offer the older pregnant pregnant woman an opportunity to reduce this risk. To determine the magnitude of potential risk reduction, the maternal age-specific incidence of infants born with 1 or more severe birth defects was reviewed in metropolitan Atlanta, Georgia, USA, during 1968-1975, removing from analysis certain anomalies that were preventable by currently available methods. For women aged 35-44 yr, 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 yr or older, although reduced considerably, was 2 times greater than that for women aged 34 yr or younger.