Objective: This study was designed to evaluate the long-term effect of a campaign to avoid prone sleeping on the sudden infant death syndrome (SIDS) mortality rate and on parents' choice of sleeping position for young infants. Before the campaign, 64% of infants usually slept prone and the SIDS rate was 3.5 (95% CI, 2.64 to 4.36) per 1000 live births.
Study design: Population-based case reference study of infants dying suddenly and unexpectedly at the ages of 1 week to 1 year, and of 493 healthy infants between 2 and 6 months of age, starting 4 years after an intervention program to avoid prone sleeping.
Results: The SIDS rate was 0.3 per 1000 live births (95% CI, 0.05 to 0.54). One of five (20%) SIDS victims usually slept prone, three of five (60%) were placed prone for their last sleep, and five of six were found dead in the prone position. Of the reference infants, 1.4% were usually placed prone to sleep, although all had previously accepted a non-prone position. Nearly half of the infants (49.1%) were usually placed supine, 22.7% usually on the side, and 26.8% in variable positions of which 2.0% occasionally included prone. The side position was the least stable position. After the age of 1 week, 59.4% of infants had been found with their heads covered on at least one occasion.
Conclusions: SIDS is rare when prone sleeping is avoided. Infants at the age of particular risk for SIDS may spontaneously turn from the side to the prone position, and they commonly slip under the bedding during sleep.