Objective: To determine the effect of sleep position, sleep location, and b
ed-sharing on the incidence of sudden unexpected death in infancy and the f
requency 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 retros
pective series was compiled from log books and files of the Medical Examine
r 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 ton the stomach), 9.7% were supine ton the back)
, 5.5% were on their side, 22.1% were in an unknown position, and 40.1% wer
e bed-sharing. Significant autopsy findings that could explain death were d
ocumented by autopsy in 37.5% of all supine and side sleeping infants and o
nly 14.0% of all prone sleeping infants (P <.001). Deaths of supine and sid
e sleeping infants were more likely to be classified as a natural disease p
rocess other than sudden infant death syndrome (P <.01). Significant autops
y findings that could explain death were found in 47.6% of the infants slee
ping atone in the supine or side position (P <.01), 18.2% of infants bed-sh
aring in the supine or side position, 16.5% of infants sleeping alone white
prone, and 9.3% of infants bed-sharing while prone.
Conclusions: infant deaths associated with the prone position were less fre
quently explained by illness or disease than infant deaths associated with
non-prone sleeping positions. Bed-sharing appears to increase the proportio
n of unexplained deaths, regardless of the position of the infant. The "Bac
k to Sleep" campaign appears to be effective in reducing the incidence of u
nexpected steeping infant deaths regardless of the certified cause of death
.