Bed-Sharing in the Absence of Hazardous Circumstances: Is There a Risk of Sudden Infant Death Syndrome? An Analysis from Two Case-Control Studies Conducted in the UK

OBJECTIVE The risk of sudden infant death syndrome (SIDS) among infants who co-sleep in the absence of hazardous circumstances is unclear and needs to be quantified. DESIGN Combined individual-analysis of two population-based case-control studies of SIDS infants and controls comparable for age and time of last sleep. SETTING Parents of 400 SIDS infants and 1386 controls provided information from five English health regions between 1993-6 (population: 17.7 million) and one of these regions between 2003-6 (population:4.9 million). RESULTS Over a third of SIDS infants (36%) were found co-sleeping with an adult at the time of death compared to 15% of control infants after the reference sleep (multivariate OR = 3.9 [95% CI: 2.7-5.6]). The multivariable risk associated with co-sleeping on a sofa (OR = 18.3 [95% CI: 7.1-47.4]) or next to a parent who drank more than two units of alcohol (OR = 18.3 [95% CI: 7.7-43.5]) was very high and significant for infants of all ages. The risk associated with co-sleeping next to someone who smoked was significant for infants under 3 months old (OR = 8.9 [95% CI: 5.3-15.1]) but not for older infants (OR = 1.4 [95% CI: 0.7-2.8]). The multivariable risk associated with bed-sharing in the absence of these hazards was not significant overall (OR = 1.1 [95% CI: 0.6-2.0]), for infants less than 3 months old (OR = 1.6 [95% CI: 0.96-2.7]), and was in the direction of protection for older infants (OR = 0.1 [95% CI: 0.01-0.5]). Dummy use was associated with a lower risk of SIDS only among co-sleepers and prone sleeping was a higher risk only among infants sleeping alone. CONCLUSION These findings support a public health strategy that underlines specific hazardous co-sleeping environments parents should avoid. Sofa-sharing is not a safe alternative to bed-sharing and bed-sharing should be avoided if parents consume alcohol, smoke or take drugs or if the infant is pre-term.