Relationship between infant death and maternal age. Comparison of sudden infant death incidence with other causes of infant mortality.

The high incidence of sudden infant death syndrome in infants born to teenage mothers prompted us to search for epidemiologic clues that might relate to SIDS causation. The death rate for SIDS was compared with that of other major causes of infant mortality in two maternal age groups (younger than 20 years and 30 to 34 years). In the neonatal period, a significantly greater overall mortality occurred in infants born to the younger mothers. This difference was primarily related to an excess of low-birth-weight infants dying from diseases of early infancy. "Weight-specific" mortality, however, was similar for the two groups. In the postneonatal period, when most SIDS occurs, the incidence was 5.2 per 1000 among infants of teenage mothers, compared with 1.0 in infants of the older mothers. A similar maternal-age-related incidence was observed for death from infections, accidents, and "other causes." By contrast, death from congenital anomalies was unrelated to maternal age in both periods. We conclude that many postneonatal deaths are influenced by environmental factors, including the age and maturity of the mother.