Sudden Infant Death Syndrome (SIDS)



  • Sudden, unexpected infant death (infant <1 yr old) (SUID) who was typically well before being placed down to sleep
  • SUID includes sudden infant death syndrome (SIDS) as well as accidental suffocation and strangulation in bed (ASSB) and unknown cause of death in infants <1 yr of age
  • SIDS deaths remain unexplained after being thoroughly investigated by autopsy, exam of the death scene, investigation of the circumstances, and review of the family and infant medical histories
  • SIDS is distinct from ASSB which occurs when something limits a baby's breathing such as a blanket against the face or the baby is trapped between two objects (e.g., mattress and wall) which has increased since 1995.
  • If nonfatal, known as BRUE (brief resolved unexplained event). Previously called ALTE (apparent life-threatening event)
  • Leading cause of death in infants 1 mo–1 yr of age; the incidence has declined markedly since the initiation of the “Back to Sleep” program in 1994:
    • 1992: 120 deaths/100,000 live births (US)
    • 2001: 56 deaths/100,000 live births (US)
    • No change from 2001–2008
    • 2009: 54 deaths/100,000 live births (US)
    • 2013: 40 deaths/100,000 live births (US)
    • 2015: 39 deaths/100,000 live births (US)
  • Peak occurrence of SIDS is 1–4 mo of age:
    • 90% occur <6 mo of age
    • 2% occur >10 mo of age
  • Ethnic differences: Using 2010–2013 data, SIDS rates for non-Hispanic black and American Indian/Alaska Native populations were much higher than non-Hispanic whites, while SID rates for Asian/Pacific Islander and Hispanic populations were much lower than non-Hispanic whites
  • Sleeping on back (supine) reduces incidence significantly (“Back to Sleep”). Practice of infants sleeping on their backs began initially in Europe and then in the U.S.


  • SIDS deaths are most likely multifactorial
  • SIDS infants likely have predisposing conditions that make them more vulnerable to both internal and external stressors
  • Potential stressors include anemia, congenital diseases, dysrhythmias, electrolyte abnormalities, genetic defects, infection, metabolic disorders, neurologic events, suffocation, trauma, and upper airway obstruction
  • Maternal and antenatal risk factors:
    • Alcohol and illicit drug use
    • Intrauterine growth restriction
    • Lower socioeconomic status
    • Poor prenatal care
    • Prior sibling death secondary to SIDS
    • Shorter interval between pregnancies
    • Smoking
    • Younger age
  • Infant risk factors:
    • Bed sharing
    • Exposure to environmental smoking
    • Gastroesophageal reflux (GER)
    • Hyperthermia
    • Low birth weight, prematurity
    • Male gender
    • Soft bedding, soft sleeping surface
    • Recent febrile illness
  • Supine sleeping position, breastfeeding, room sharing without bed sharing (especially in the first 6 mo), and pacifier use are protective
  • Home monitoring has not been shown to prevent SIDS

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