Sudden infant death syndrome

Last reviewed: 7 Jan 2023
Last updated: 11 Oct 2019



History and exam

Key diagnostic factors

  • prone, side, or inclined position at last sleep
  • bed-sharing
  • soft sleeping environment
  • maternal cigarette smoking
  • premature birth
  • formula feeding
  • non-use of pacifier
  • maternal alcohol or drug use
More key diagnostic factors

Other diagnostic factors

  • absence of metabolic disease
  • absence of irritability, lethargy
  • absence of fever, cough, or nasal congestion
  • absence of trauma
Other diagnostic factors

Risk factors

  • side, prone, or inclined position at last sleep
  • bed-sharing/co-sleeping
  • soft sleeping surface/environment
  • maternal cigarette smoking
  • increasing number of smokers in house
  • smoking in same room as child
  • formula feeding
  • non-use of a pacifier
  • premature birth
  • maternal substance use/abuse
  • single mother
  • lower maternal age
  • low level of prenatal care
  • low level of maternal education
  • low socioeconomic status
  • black or American Indian
  • lack of immunization
More risk factors

Diagnostic investigations

Investigations to consider

  • blood culture
  • cerebrospinal fluid culture
  • urine culture
  • serum chemistry
  • urine chemistry
  • photographic record
  • skeletal survey
  • anatomic pathology
  • vitreous chemistry
  • muscle biopsy
More investigations to consider

Treatment algorithm


caregivers and family



Rachel Y. Moon, MD, FAAP

Professor of Pediatrics

University of Virginia School of Medicine




RYM receives grant funding from the National Institutes of Health, receives honoraria for speaking at various conferences, and is a board member of the International Society for the Study and Prevention of Perinatal and Infant Death. She has provided expert testimony in a case of an infant who died suddenly and unexpectedly.


Dr Rachel Y. Moon would like to gratefully acknowledge Dr John W. Berkenbosch, a previous contributor to this topic.


JWB declares that he has no competing interests.

Peer reviewers

Peter Fleming, MB ChB, PhD

Professor of Infant Health & Developmental Physiology

FSID Research Unit

Institute of Child Life and Health

St Michaels Hospital




PF is an author of a number of references cited in this topic.

Thomas Hegyi, MD

Professor and Vice-Chair

Department of Pediatrics

UMDNJ-Robert Wood Johnson Medical School

New Brunswick



TH declares that he has no competing interests.

  • Differentials

    • Accidental suffocation or asphyxia
    • Nonaccidental trauma or abusive injury, including Munchausen syndrome by proxy
    • Respiratory syncytial virus
    More Differentials
  • Guidelines

    • Sudden infant death syndrome: evidence base
    • Co-sleeping and SIDs: a guide for health professionals
    More Guidelines
  • Patient leaflets

    Sudden infant death syndrome: how can I reduce the risk?

    More Patient leaflets
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