Sudden infant death syndrome among twins in the United States 1995--1997

Abstract

Sudden infant death syndrome (SIDS) constitutes an increasing proportion of infant deaths, and twins have a higher risk of SIDS than singletons. This retrospective cohort study, based on the 1995-1997 Matched Multiple Birth File of the United States, examined risk factors of SIDS and non-SIDS deaths using generalized estimating equations, and investigated competing risks of SIDS using survival analysis. The three unique characteristics of twins, namely birth weight discordance, birth order within pairs, and sex combinations, were not associated with SIDS, while they were related to non-SIDS deaths. Lower maternal education, younger maternal age, and maternal smoking during pregnancy were the strongest risk factors of SIDS among twins. Preterm birth and fetal growth restriction were determinants of infant deaths, including both SIDS and non-SIDS deaths. In conclusion, social factors and common biological factors are important risk factors for SIDS among twins while the biological factors unique to twins are not.