Article Text

Bed sharing when parents do not smoke: is there a risk of SIDS? An individual level analysis of five major case–control studies
  1. Robert Carpenter1,
  2. Cliona McGarvey2,
  3. Edwin A Mitchell3,
  4. David M Tappin4,
  5. Mechtild M Vennemann5,
  6. Melanie Smuk1,
  7. James R Carpenter1,6
  1. 1Department of Medical Statistics, London School of Hygiene & Tropical Medicine, London, UK
  2. 2National SIDS Register, The Children's University Hospital, Dublin, Ireland
  3. 3Department of Paediatrics, University of Auckland, Auckland, New Zealand
  4. 4Department of Child Health, University of Glasgow, Glasgow, UK
  5. 5Institute of Legal Medicine, University of Muenster, Münster, Germany
  6. 6MRC Clinical Trials Unit, Kingsway, London, UK
  1. Correspondence to Professor R G Carpenter; bob.carpenter{at}


Objective To resolve uncertainty as to the risk of Sudden Infant Death Syndrome (SIDS) associated with sleeping in bed with your baby if neither parent smokes and the baby is breastfed.

Design Bed sharing was defined as sleeping with a baby in the parents’ bed; room sharing as baby sleeping in the parents’ room. Frequency of bed sharing during last sleep was compared between babies who died of SIDS and living control infants. Five large SIDS case–control datasets were combined. Missing data were imputed. Random effects logistic regression controlled for confounding factors.

Setting Home sleeping arrangements of infants in 19 studies across the UK, Europe and Australasia.

Participants 1472 SIDS cases, and 4679 controls. Each study effectively included all cases, by standard criteria. Controls were randomly selected normal infants of similar age, time and place.

Results In the combined dataset, 22.2% of cases and 9.6% of controls were bed sharing, adjusted OR (AOR) for all ages 2.7; 95% CI (1.4 to 5.3). Bed sharing risk decreased with increasing infant age. When neither parent smoked, and the baby was less than 3 months, breastfed and had no other risk factors, the AOR for bed sharing versus room sharing was 5.1 (2.3 to 11.4) and estimated absolute risk for these room sharing infants was very low (0.08 (0.05 to 0.14)/1000 live-births). This increased to 0.23 (0.11 to 0.43)/1000 when bed sharing. Smoking and alcohol use greatly increased bed sharing risk.

Conclusions Bed sharing for sleep when the parents do not smoke or take alcohol or drugs increases the risk of SIDS. 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.

  • Prevention
  • Public Health
  • Epidemiology
  • Sids
  • Bed sharing

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: and

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Supplementary materials

  • Supplementary Data

    This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

    Files in this Data Supplement: