Objective: To determine the effect of sleep position, sleep location, and bed-sharing on the incidence of sudden unexpected death in infancy and the frequency of significant autopsy findings.
Methods: We evaluated the cause of death in infants <1 year of age who died during sleep from January 1, 1986, through September 30, 1999. This retrospective series was compiled from log books and files of the Medical Examiner Office, Palm Beach County, Florida.
Results: The incidence of sudden unexpected infant death decreased 50% over the study period (P <.01). Of the 217 infants that fit the study criteria, 62.7% were sleeping prone (on the stomach), 9.7% were supine (on the back), 5.5% were on their side, 22.1% were in an unknown position, and 40.1% were bed-sharing. Significant autopsy findings that could explain death were documented by autopsy in 37.5% of all supine and side sleeping infants and only 14.0% of all prone sleeping infants (P <.001). Deaths of supine and side sleeping infants were more likely to be classified as a natural disease process other than sudden infant death syndrome (P <.01). Significant autopsy findings that could explain death were found in 47.6% of the infants sleeping alone in the supine or side position (P <.01), 18.2% of infants bed-sharing in the supine or side position, 16.5% of infants sleeping alone while prone, and 9.3% of infants bed-sharing while prone.
Conclusions: Infant deaths associated with the prone position were less frequently explained by illness or disease than infant deaths associated with non-prone sleeping positions. Bed-sharing appears to increase the proportion of unexplained deaths, regardless of the position of the infant. The "Back to Sleep" campaign appears to be effective in reducing the incidence of unexpected sleeping infant deaths regardless of the certified cause of death.