Size for gestational age at birth: Impact on risk for sudden infant death and other causes of death, United States 2002

Abstract

Background: Small for gestational age (SGA) infants have been reported to be at higher risk for Sudden Infant Death Syndrome (SIDS).

Objective: The objective of this analysis was to compare the risk of SIDS among SGA and large for gestational age (LGA) infants to the risk of death from other causes of sudden unexpected deaths in infancy (SUDI) and the residual “Other” causes of infant death.

Methods: The 2002 U.S. period infant birth and death certificate linked file was used to identify infant deaths which were classified as due to either SIDS (ICD-10 code R95) or SUDI (ICD-10 codes R00-Y84 excluding R95) or all other residual codes. Race and sex specific birth cohorts for the year 2002 were used to generate the 10th and 90th percentiles of birth weight for each gestational age week from 24 to 42 weeks gestation. Birth weights < 10th percentile were designated SGA and greater than the 90th percentile LGA. Demographic variables previously identified as associated with SIDS were used in multiple logistic regression equations to determine the risk for death among SGA and LGA infants independent of other potentially confounding variables.

Results: There were 1,956 SIDS deaths, 2,012 SUDI, and 11,592 other deaths with complete data available for analysis. The adjusted odds ratio for SIDS for SGA infants was 1.65 (1.47, 1.85), for SUDI 1.78 (1.59, 2.00) and for all “Other” causes 4.68 (4.49, 4.88). The adjusted odds ratios for LGA infants was reduced for SIDS, OR=0.73 (0.60, 0.89); SUDI, OR=0.81 (0.68, 0.98); and “Other”, OR= 0.42 (0.38, 0.46).

Conclusion: Although SGA infants appear to be at slightly increased risk for SIDS or SUDI their risk for “Other” residual causes is about 2.5 times higher. Large for gestational age infants appear to be at reduced risk of mortality for all causes. The mechanisms by which restricted intrauterine growth increases risk of mortality while excessive intrauterine growth offers protective effects is uncertain.