Since the “Back to Sleep” campaign in the UK fifteen years ago, in which parents were advised to put their babies down to sleep on their backs, the number of deaths from sudden infant death syndrome (SIDS) in England and Wales has fallen by 75%. A consequence of this seems to have been that socioeconomic deprivation, which has always been a factor increasing the risk of SIDS, has become even more prominent. A study in the county of Avon (

) has illustrated this change and pointed also to the danger of sleeping with an infant on a sofa.

Since 1984 paediatricians in Avon have been notified of all sudden unexpected deaths in infancy (SUDI); and have interviewed the family soon after the death. An autopsy has been performed by a paediatric pathologist and the cause of death classified by a multidisciplinary group. Over a period of 20 years data were collected about 369 cases of SUDI, of which 300 were unexplained (SIDS). There were 158 cases of SIDS in 1984–88 and 36 in 1999–2003. The proportion of SIDS families in social classes IV or V or unemployed was 47% in 1984–88 and 74% in 1999–2003. In a control population in 1993–96 this proportion was 17%. Before 1991 28% of SIDS families had no income from employment; after 1991 this figure rose to 48%. The proportion living in the lowest 10% of areas for social deprivation rose from 23% in 1984–88 to 48% in 1999–2003. The prevalence in SIDS families of factors associated with social deprivation also rose: single mothers from 15% to 40%, mothers under 20 years old from 7% to 16%, maternal smoking in pregnancy from 57% to 86%. The proportion born preterm rose from 12% to 34%, multiple births from 2% to 8%, families of more than three children from 14% to 36%, and first children from 18% to 33%. The proportion of mothers who had tried to breastfeed fell from 50% to 26%.

The proportion of infants who had been in bed with their parents at the time of death rose from 11% to 39%. The absolute numbers of infants dying in these circumstances has, however, fallen so the increased proportion may, at least in part, be due to the fall in SIDS rate among infants sleeping alone. Between 1984 and 1991 two infants had died whilst sleeping with a parent on a sofa; between 1992 and 2003 nine infants died in these circumstances (four of 36 SIDS deaths in 1999–2003).

SIDS is now even more strongly associated with social deprivation. Parents should be warned against sleeping with infants in their bed and particularly against sleeping with an infant on a sofa.