In a case-series analysis of 157 SIDS-related deaths that occurred in Quebec between 1991 and 1997, Dr. Aurore Côté of the Montreal Children's Hospital found that 34 of 64 nonprone sleepers had been placed in the prone position by a parent or caregiver before death, while another 18 appear to have rolled on to their belly for the first time (Pediatrics 2000;106[6]:E86).

Among the 34 infants who changed to the prone position, 21 had their sleeping position switched less than 1 week before their death; 16 of 21 died the first or second time they slept on their stomach.

Côté found that in 56% of cases where an infant was changed to the prone position, a caregiver other than the parents had made the switch. Many caregivers simply were unaware that the prone position is not recommended.

"People in general, and also health professionals, are still afraid of the back position," said Côté, who has been studying SIDS since 1987. "They believe that babies can aspirate regurgitated milk, secretions or vomitus."