Sudden infant death syndrome among twin births: United States, 1995-1998.

OBJECTIVES: To compare the incidence and risk factors for sudden infant death syndrome (SIDS) in twin and singleton births and to estimate the concordance of SIDS in twins. STUDY DESIGN: A cohort analysis using the National Center for Health Statistics Linked Birth and Infant Death files (1995-1998). RESULTS: Twins had higher SIDS rate (1.3/1000 live births) compared to singletons (0.7/1000 live births), relative risk: 1.9, 95% confidence interval: 1.68, 2.01. Male and small- for-gestational age infants as well as infants of black, unmarried, and smoking mothers were at increased risk for SIDS in both twins and singletons. Placental abnormalities also were associated with SIDS in singletons and twins, although this association failed to achieve statistical significance in twins. There is a higher rate of SIDS in the second twin after a first twin SIDS. CONCLUSIONS: Twins are at higher risk of SIDS than are singletons. Overall, the epidemiology of SIDS in twins is quite similar to that seen in singletons.