Major changes in the epidemiology of Sudden Infant Death Syndrome: a 20-year population based study of all unexpected deaths in infancy

249 words (limit 250 words) Background: Recent case-control studies suggest the epidemiology of Sudden Infant Death Syndrome (SIDS) may have changed since the 1991 ‘Back to Sleep’ campaign and subsequent fall in rates. A unique collection of longitudinal data is used to measure these potential changes. Methods: Population-based data from home visits have been collected for 369 consecutive unexpected infant deaths (300 SIDS and 69 explained deaths) in Avon over a 20-year period (1984-2003). Data collected between 1993-6 from 1300 control infants with a chosen sleep prior to interview has also been used for reference. Findings: Social deprivation was increasingly more common amongst SIDS families; the proportion of social class IV,V & unemployed families rose from 47% to 74% (p<0.003), 86% of the mothers smoke, 40% are now single, and 16% are aged less than 20. Although many SIDS infants come from large families, first-born infants are now the most common group. The proportion of co-sleeping SIDS deaths increased from 12% to 50% (p<0.0001), but the actual number of SIDS deaths in the parental bed fell significantly (p=0.01). This rise in proportion is due partly to the limited effect of the “Back to Sleep” campaign on factors in this sleeping environment and partly to a rise in the number of bedsharing deaths on sofas. Infants who die as SIDS whilst bedsharing are now 4-5 weeks younger at death than in the 1980’s. Interpretation: Changes in the epidemiology of SIDS have implications both in the interpretation of causal mechanisms and how we should conduct future studies. Avon SIDS epidemiology paper 18/11/2008 3