Intrauterine growth retardation and risk of sudden infant death syndrome (SIDS)

The purpose of this study was to assess whether intrauterine growth retardation was associated with an increased risk of sudden infant death syndrome (SIDS). A total of 148 SIDS cases were identified from the Upstate New York (exclusive of New York City) live birth cohort for 1974 (n = 132,948). Dead controls represented all other sudden deaths (n = 114). Live controls were randomly selected and matched to cases on mother's age, race, parity, and residence and infant's birth date (n = 355). Data were collected from vital certificates (response, 97%), medical records (89%), and autopsy reports (100%). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with the use of logistic regression techniques to control for confounding. With live controls, significant risks were observed for gestations less than 37 weeks (OR = 2.2, CI 1.2-4.1), birth weights less than 2,500 g (OR = 2.5, CI 1.3-5.0) and birth lengths less than or equal to 47.0 cm (OR = 3.4, CI 1.8-6.4). Birth length less than or equal to 47.0 cm was the only significant risk factor observed when dead controls were used (OR = 2.9, CI 1.3-6.8). Risk decreased with increasing gestation and birth size. Postterm infants (greater than or equal to 42 weeks) were at lowest risk (live controls OR = 0.9, CI 0.5-1.6; dead controls OR = 0.6, CI 0.3-1.1). When gestational age was controlled for, SIDS infants were found to have reductions in both weight and length; this suggests that responsible mechanisms begin early in pregnancy.