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Environment of infants during sleep and risk of the sudden infant death syndrome: results of 1993-5 case-control study for confidential inquiry into stillbirths and deaths in infancy

BMJ 1996; 313 doi: (Published 27 July 1996) Cite this as: BMJ 1996;313:191
  1. Peter J Fleming, professor of infant health and developmental physiologya,
  2. Peter S Blair, medical statisticiana,
  3. Chris Bacon, consultant paediatricianb,
  4. David Bensley, statisticianc,
  5. Iain Smith, senior lecturerd,
  6. Elizabeth Taylor, consultant senior lecturer in paediatricse,
  7. Jem Berry, professor of paediatric pathologyf,
  8. Jean Golding, professor of paediatric and perinatal epidemiologyg,
  9. John Tripp, consultant paediatricianh

    Confidential Enquiry into Stillbirths and Deaths Regional Coordinators and Researchers

  1. a Foundation for the Study of Infant Deaths Research Unit, Institute of Child Health, Royal Hospital for Sick Children, Bristol BS2 8BJ
  2. b Friarage Hospital, Northallerton, North Yorkshire DL6 1JG
  3. c Operational Research Division, NHS Executive, Quarry House, Leeds LS2 9UA
  4. d Nuffield Institute for Health, Leeds LS2 9PL
  5. e Sheffield Children's Hospital, Sheffield S10 2TH
  6. f University of Bristol, St Michael's Hospital, Bristol BS2 8EG
  7. g Institute of Child Health, Royal Hospital for Sick Children, Bristol BS2 8BJ
  8. h Department of Child Health, Postgraduate Medical School, Royal Devon and Exeter Hospital, Exeter EX2 5DW
  1. The regional coordinators and researchers of the confidential inquiry into stillbirths and deaths in infancy are given at the end of this article. Correspondence to: Professor Fleming
  • Accepted 19 June 1996


Objective: To investigate the role of sleeping arrangements as risk factors for the sudden infant death syndrome after a national risk reduction campaign.

Design: Two year population based case-control study. Parental interviews were conducted for each infant who died and for four controls matched for age and date of interview.

Setting: Three regions in England with a total population of 17 million people.

Subjects: 195 babies who died and 780 matched controls.

Results: Prone and side sleeping positions both carried increased risks of death compared with supine when adjusted for maternal age, parity, gestation, birth weight, exposure to smoke, and other relevant factors in the sleeping environment (multivariate odds ratio = 9.00 (95% confidence interval 2.84 to 28.47) and 1.84 (1.02 to 3.31), respectively). The higher incidence of side rather than prone sleeping led to a higher population attributable risk (side 18.4%, prone 14.2%). More of the infants who died were found with bed covers over their heads (21.58; 6.21 to 74.99). The use of a dummy had an apparent protective effect (0.38; 0.21 to 0.70). Bed sharing for the whole night was a significant risk factor for infants whose mothers smoked (9.25; 2.31 to 34.02). No protective effect of breast feeding could be identified on multivariate analysis.

Conclusions: This study confirms the importance of certain risk factors for the sudden infant death syndrome and identifies others—for example, covers over the head, side sleeping position—which may be amenable to change by educating and informing parents and health care professionals.

Key messages

  • This large case-control study is the first after the national campaign to reduce the risk of the syndrome

  • The risk of sudden infant death is increased by prone or side sleeping position; loose bedding (particularly duvets), which can slip over the baby's head; and bed sharing by mothers who smoke

  • The risk may be reduced by supine sleeping position; placing the baby with feet at the foot of the cot (“feet to foot”); ensuring that bedding is securely tucked in; and avoiding the use of duvets


  • Funding National Advisory Body for the confidential inquiry into stillbirths and deaths in infancy.

  • Conflict of interest None.

  • Accepted 19 June 1996
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