Birth Weight- and Gestational Age-Specific Sudden Infant Death Syndrome Mortality: United States, 1991 Versus 1995

Objective. To estimate the changes in birth weight- and gestational age-specific sudden infant death syndrome (SIDS) mortality rates since the publication of the sleep-positioning recommendations by the American Academy of Pediatrics Task Force on Infant Positioning and SIDS.

Methods. This is a historical cohort study using US vital statistic linked birth and infant death certificate files for the years 1991 and 1995. SIDS deaths were identified as any death attributed toInternational Classification of Diseases, Ninth Revisioncode 7980, occurring between the 28th and 365th days of life.

Results. There were 4871 deaths attributed to SIDS in 1991 for a postneonatal mortality rate of 1.2/1000 postneonatal survivors compared with 3114 deaths in 1995 for a rate of .8/1000. This represents a 33% drop in the postneonatal SIDS mortality from 1991 to 1995. Between 1991 and 1995, SIDS rates declined 38%, 38%, 35%, and 32% for birth weight groupings of 500 to 999 g, 1000 to 1499 g, 1500 to 2499 g, and ≥2500 g, respectively. There were no SIDS deaths attributed to infants weighing <500 g. The SIDS rates declined 27%, 21%, 40%, and 23% for gestational age groups of <29 weeks, 29 to 32 weeks, 33 to 36 weeks, and ≥37 weeks. The rate of decline did not differ significantly across birth weight- or gestational age-specific categories. There was a significant increase in the black:non-black postneonatal SIDS mortality ratio from 2.00 to 2.28, reflecting a smaller decline in birth weight- and gestational age-specific mortality for blacks than observed for the non-black population.

Conclusion. Postneonatal SIDS mortality decreased significantly across all broad birth weight and gestational age categories. If the decline in the prevalence of prone positioning that has been reported since 1992 has occurred across all birth weight and gestational age, these data support the hypothesis that supine or side sleep positioning is effective in preterm/low birth weight infants as well as term infants.