NEW YORK (Reuters Health) - There has been a continuing decline in the number of sudden infant death syndrome (SIDS) cases following the initial drop that occurred after parents were urged to avoid placing their infants face down to sleep. Researchers suggest that this continuing decline is due to a further change from the side to back positioning of infants before bed.

There was an initial 50-percent fall in SIDS rates from the mid-1980s to 1993, at which time nearly no infants were placed on their stomachs to sleep. Dr. Edwin A. Mitchell and colleagues from the University of Auckland, New Zealand, hypothesized that the continued decline is because fewer infants are being placed on their side to sleep.

The researchers sent a questionnaire in April-May 2005 to a random sample of 400 mothers who had delivered infants at the National Women's Hospital in Auckland. They were asked which position they put their baby to sleep in the previous night. The findings are published in the Archives of Disease in Childhood.

Based on the 278 usable responses, 72.3 percent of infants were placed on their backs; 14.0 percent on their sides; 12.2 percent on their sides and backs; and 1.4 percent on their stomachs.

SIDS deaths declined by 63 percent from 1993 to 2004, according to data from New Zealand Health Information Service.

The researchers conclude that the continuing decline in SIDS "is likely to be due to the substantial increase in the proportion of infants placed to sleep on their back rather than on their side."