INFLUENCE OF INCREASED SURVIVAL IN VERY-LOW-BIRTH-WEIGHT, LOW-BIRTH-WEIGHT, AND NORMAL BIRTH-WEIGHT INFANTS ON THE INCIDENCE OF SUDDEN-INFANT-DEATH-SYNDROME IN THE UNITED-STATES - 1985-1991

Objective: To examine the relationship between infant survival and the rates of sudden infant death syndrome (SIDS) in very low birth weight (VLBW), low birth weight (LBW), and normal birth weight (NBW) infants from 1985 to 1991. Methods: The National Center for Health Statistics Birth Cohort Linked Birth/Infant Death Data Sets were used to determi ne birth weight, age at death, and cause of death for US-born singleto n infants with birth weights of 500 g or more. Results: Increasing inf ant and postneonatal survival rates were greatest in VLBW infants. In contrast, SIDS rates did not change in VLBW infants (3.66 to 3.69; P = .70) but declined in both LBW (3.51 to 3.32; P = .041) and NBW (1.07 to 1.03; P = .008) infants. Postneonatal SIDS rates (per 1000 neonatal survivors) did not change in VLBW (4.93 to 4.58; P = .58) or LBW (3.3 6 to 3.22; P = .07) infants but declined in NBW infants (1.00 to 0.97; P = .018). Although there were differences among the slopes of surviv al rates, there was no statistical evidence of differences in the slop e of SIDS rates among the three groups. Conclusions: The marked increa se in survival of VLBW infants increased the pool of babies at potenti al risk for SIDS. VLBW infants' SIDS rates have not changed while they have declined in NBW and LBW infants.