Objective: To identify the risk factors for infants who die suddenly and unexpectedly, but whose deaths are not related to prone position, or having the head covered.
Methodology: A case-control study was designed in which the cases were infants who had died of sudden infant death syndrome (SIDS) in South Australia between January 1974 and December 1997, who were found not prone, not bed sharing and with the head not covered. The controls were two infants for each case, born in the same year and found in the prone position (again not bed sharing and with the head not covered).
Results: Sudden unexpected death in infancy is rare in non-prone infants with the head not covered, occurring on average twice a year in South Australia, where there are 18 000–21 000 births per year. In this group there was a higher percentage of infants with features associated with low socio-economic groups (teenage pregnancies and maternal smoking), sibling SIDS, suspicion of non-accidental injury and the presence of minor congenital anomalies, especially cardiac anomalies.
Conclusions: The majority of unexpected deaths in infancy can be prevented by not allowing infants to be unobserved in prone position, and by preventing them from getting their faces covered. For the few infants not found in these positions, a careful investigation should be made for malformations or non-accidental injury.