Sudden infant death syndrome and maternal age: etiologic implications.

During a 12-year period (1969 through 1980), 431 episodes of sudden infant death syndrome (SIDS) occurred in King County, Washington. Longitudinal analysis of these data confirms the inverse association of SIDS occurrence with maternal age, which has been reported repeatedly from previous cross-sectional analyses. Risk of SIDS increases with increasing birth order, but the inverse maternal age gradient remains constant within each birth-order category. Available evidence suggests that maternal age may be a more important clue to SIDS causation than previously supposed. Assessment of established SIDS risk factors in relation to maternal age deserves further attention. The role of nutrition of pregnancy in relation to maternal age and SIDS risk may also be a productive avenue for future investigation.