When neither parent smoked, and the baby was breastfed, less than 3-months old, and had no other major SIDS risk factors, the adjusted odds ratio for bed-sharing versus room-sharing was still 5.1 (2.3 to 11.4), reported Robert Carpenter PhD, from the London School of Hygiene and Tropical Medicine, and colleagues, in the online journal BMJ Open.
The estimated absolute risk for bed-sharing compared with room-sharing was 0.23/1,000 live births (0.11 to 0.43) versus 0.08/1,000 live births, they added.
Nine out of 10 SIDS deaths that involved sleeping with a parent or caregiver would not have occurred in the absence of bed-sharing, the researchers concluded.
Advice on bed-sharing varies by country, but "there is general acceptance that sleeping with a baby is a risk factor for SIDS when sleeping ... in a bed if the mother smokes and/or has taken alcohol," the authors explained. But there's less consensus on whether bed-sharing is still a problem with the absence of these risk factors.
The study combined five major case-control trials conducted in the U.K. and Europe, as well as in Australia and surrounding countries, that included 1,472 infant SIDS deaths and 4,679 controls, making it the largest study of SIDS risk factors ever reported, according to the authors.
Bed-sharing was defined as sleeping in the same bed with one or both parents, while room-sharing was defined as sleeping in a crib in the same room as a parent.
Image: Baby in bed, via Shutterstock