SIDS Risk May Be Fivefold Higher With Bed Sharing

Laurie Barclay, MD

May 22, 2013

Parents could dramatically lower their infants' risk for sudden infant death syndrome (SIDS) by not sharing beds with their young child, according to an individual-level analysis of 5 major case–control studies published online May 20 in BMJ Open.

"The proposition that bed sharing is causally related to SIDS is coherent with theories that respiratory obstruction, re-breathing expired gases, and thermal stress...are all mechanisms leading to SIDS," write Robert Carpenter, PhD, from the London School of Hygiene & Tropical Medicine in the United Kingdom, and colleagues. "Infants placed prone are exposed to similar hazards."

The rate of SIDS has declined since parents have been being counseled to place babies to sleep in the supine position. Nonetheless, in developed countries, SIDS remains the leading cause of infant death in the postneonatal period.

The study goal was to clarify the risk for SIDS associated with parents sleeping in bed with their infant if neither parent smokes and the infant is breast-fed. The investigators combined 5 large SIDS case–control data sets regarding the home sleeping arrangements of infants in 19 studies across the United Kingdom, Europe, and Australasia. Standard criteria allowed identification of 1472 SIDS cases, and 4679 control participants who had been randomly selected from normal infants of similar age, study time, and location.

The investigators compared the frequency of bed sharing, defined as sleeping with a baby in the parents' bed, during last sleep between babies who died from SIDS and living control infants. Missing data were imputed, and random effects logistic regression allowed controlling for confounding factors.

Study Findings and Implications

Bed sharing during last sleep occurred in 22.2% of cases and 9.6% of controls. Adjusted OR (AOR) for all ages was 2.7 (95% confidence interval [CI], 1.4 - 5.3). As infant age increased, bed-sharing risk decreased. For bed sharing vs room sharing (sleeping in the same room as the parents), the AOR was 5.1 (95% CI, 2.3 - 11.4) when neither parent smoked and the baby was younger than 3 months, breast-fed, and had no other risk factors. Models were adjusted for position last left, parental smoking, mother's alcohol intake over last 24 hours, mother's illegal drug use, bottle feeding, sex, whether matched or unmatched, race, birth weight group, mother’s age group, number of live births (grouped), mother single, and where slept.

Among room-sharing infants, the estimated absolute risk for SIDS was very low (0.08/1000 live births; 95% CI, 0.05 - 0.14 per 1000 live births) compared with bed-sharing infants (0.23/1000; 95% CI, 0.11 - 0.43 per 1000 live births). Bed-sharing risk increased greatly when the parents were smokers or used alcohol.

"Bed sharing for sleep when the parents do not smoke or take alcohol or drugs increases the risk of SIDS," the study authors write. "Risks associated with bed sharing are greatly increased when combined with parental smoking, maternal alcohol consumption and/or drug use. A substantial reduction of SIDS rates could be achieved if parents avoided bed sharing."

They conclude, "The current messages saying that bed sharing is dangerous only if you or your partner are smokers, have been drinking alcohol or taking drugs that make you drowsy, are very tired or the baby is premature or of low-birth weight, are not effective because many of the bed sharing deaths involve these factors. Our findings suggest that professionals and the literature should take a more definite stand against bed sharing, especially for babies under 3 months. If parents were made aware of the risks of sleeping with their baby, and room sharing were promoted, as 'Back to Sleep' was promoted 20 years ago, a substantial further reduction in SIDS rates could be achieved."

Original data collection was funded by the European Concerted Action on SIDS, the European Union and the Foundation for the Study of Infant Deaths; Irish SIDS study, Irish Department of Health and Children; New Zealand Cot Death Study, the Health Research Council of New Zealand; Scottish Cot Death Study, Scottish Cot Death Trust; and the German Study on Sudden Infant Death, Federal Ministry of Education and Research. This combined analysis and report received no additional support. Some of the study authors report various financial disclosures with the Lullaby Trust's Care of Next Infant, CONI, project, MRC Clinical Trials Unit London, London School of Hygiene & Tropical Medicine, Cure Kids, and/or the Economic and Social Research Council.

BMJ Open. Published online May 20, 2013. Full text