Investigators collected information about 300 cases of sudden infant death syndrome (SIDS) in the United Kingdom county of Avon during a 19-year period (1984 to 2003) to determine how the prevalence of variables associated with SIDS has changed. Since the start of the UK Back to Sleep campaign in 1991, the number of deaths from SIDS has fallen by 75% in England and Wales.  

The biggest change was in the sleeping environment associated with SIDS. Before the campaign, 12% of children who died from SIDS had been cosleeping with parents; that percentage has risen to 50%, even though the actual number of SIDS deaths in the parental bed has halved-a reflection of the overall reduction in SIDS deaths. The actual number of SIDS deaths that occurred while cosleeping on a sofa rose, however.  

 Previously identified characteristics of SIDS families have become increasingly prevalent, the study showed. The percentage of deaths in families from a deprived socioeconomic background rose from 47% to 74%; the prevalence of maternal smoking during pregnancy, from 57% to 86%; and the percentage of preterm infants, from 12% to 34%. SIDS infants also tended to be first born (these infants were previously thought to be at lower risk than later-born siblings), male, from a large family, and part of a multiple birth. In addition, since the campaign began, the percentage of mothers of SIDS children who attempted to breastfeed has fallen by half and the age of bed-sharing SIDS infants has dropped significantly (Blair PS et al: 