Ambient Temperature and Sudden Infant Death Syndrome in the United States

Abstract

Background: Sudden infant death syndrome (SIDS) is a leading cause of infant mortality in the United States. While thermal stress is implicated in many risk factors for SIDS, the association between ambient temperature and SIDS remains unclear. Methods: We obtained daily individual-level infant mortality data and outdoor temperature data from 1972 to 2006 for 210 United States cities. We applied a time-stratified case-crossover analysis to determine the effect of ambient temperature on the risk of SIDS by season. We stratified the analysis by race, infant age, and climate. Results: There were a total of 60,364 SIDS cases during our study period. A 5.6°C (10°F) higher daily temperature on the same day was associated with an increased SIDS risk of 8.6% (95% confidence interval (CI): 3.6%, 13.8%) in the summer, compared to a 3.1% decrease (95% CI: -5.0%, -1.3%) in the winter. Summer risks were greater among Black infants (18.5%, 95% CI: 9.3%, 28.5%) than White infants (3.6%, 95% CI: -2.3%, 9.9%), and among infants 3-11 months old (16.9%, 95% CI: 8.9%, 25.5%) than infants 0-2 months old (2.7%, 95% CI: -3.5%, 9.2%). The temperature-SIDS association was stronger in climate clusters in the Midwest and surrounding northern regions. Conclusions: Temperature increases were associated with an elevated risk of SIDS in the summer, particularly among infants who were Black, 3 months and older, and living in the Midwest and surrounding northern regions. Our findings suggest that mitigating heat exposure can further reduce SIDS rates.