Atmospheric pressure and sudden infant death syndrome in Cook County, Chicago.

We investigated daily deaths from sudden infant death syndrome (SIDS) in Cook County, Chicago, from 1 January 1986 to 31 December 1990. The daily SIDS rate was 0.54 deaths/day. Mean daily atmospheric pressure ranged from 952 to 1007 mb. We found a weak link with barometric pressure, whereby an increase of 10 mb was associated with an increased risk of 12% [95% CI 0.1%, 24%]. Cross-tabulation revealed that the highest SIDS rates were associated with a drop from high to low pressure. Possible reasons for this are discussed.