Sudden infant death syndrome

Last reviewed: 2 Sep 2023
Last updated: 19 May 2023



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 parent
  • lower maternal age
  • low level of prenatal care
  • low level of maternal education
  • low socioeconomic status
  • 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 research grants from the National Institutes of Health and the American SIDS Institute on SIDS-related topics. RM is an unpaid board member of the International Society for the Prevention of Infant Death. RM lectures at various hospitals, public health departments, and universities about SIDS-related topics (usual honorarium $1000). RM has two published books about SIDS and receives royalties (<$200/year).


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

    • Sleep-related infant deaths: updated 2022 recommendations for reducing infant deaths in the sleep environment
    • Evidence base for 2022 updated recommendations for a safe infant sleeping environment to reduce the risk of sleep-related infant deaths
    More Guidelines
  • Patient leaflets

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

    More Patient leaflets
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