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 US 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 with 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 old and older, and living in the Midwest and surrounding northern regions.