Leading cause of infant death beyond the neonatal period.
Incidence roughly 1 in 2000 infants.
Peak incidence between 1 and 3 months of age, although events may occur up to 12 months of age.
Risk factors include exposure to tobacco smoke (antenatally and postnatally); prone and side sleeping; bed-sharing during sleep; a sleep environment that includes soft mattress and/or sleeping surface (including sofa or armchair), and placement of soft sleep bedding; over-bundling/over-heating; prematurity; exposure to alcohol and illicit drugs (antenatally and postnatally); and viral infection. Several risk factors may co-exist in any given patient.
Protective factors include use of a dummy during sleep, immunisation, and breastfeeding.
Careful evaluation of death by trained forensics teams is necessary to rule out other causes of death, including suffocation, asphyxia, entrapment, infection, ingestions, metabolic diseases, arrhythmia-associated cardiac channelopathies, and trauma (accidental or non-accidental).
The term 'sudden infant death syndrome' (SIDS) was first used, and an early definition described, at the 2nd International Conference on the Causes of Sudden Death in Infants in 1969. In 1991, the definition was modified by a panel convened by the National Institute of Child Health and Human Development. The panel defined SIDS as "The sudden death of an infant under 1 year of age, which remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and a review of the clinical history". This remains the widely accepted definition, and is the preferred definition of the American Academy of Pediatrics Task Force on Sudden Infant Death Syndrome. Although some have advocated the addition of the criterion that onset of the fatal event seems to be associated with sleep, this criterion remains controversial.
History and exam
Key diagnostic factors
- presence of risk factors
Other diagnostic factors
- absence of metabolic disease
- absence of irritability, lethargy
- absence of fever, cough, or nasal congestion
- absence of trauma
- side, prone, or inclined position at last sleep
- 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 dummy
- premature birth
- maternal substance use/abuse
- single mother
- lower maternal age
- low level of antenatal care
- low level of maternal education
- low socio-economic status
- black or American Indian
- lack of immunisation
Investigations to consider
- blood culture
- cerebrospinal fluid culture
- urine culture
- serum chemistry
- urine chemistry
- photographic record
- skeletal survey
- anatomical pathology
- vitreous chemistry
- muscle biopsy
carers and family
- Accidental suffocation or asphyxia
- Non-accidental trauma or abusive injury, including Munchausen's syndrome by proxy
- Respiratory syncytial virus
- Postnatal care
- Co-sleeping and SIDs: a guide for health professionals
Sudden infant death syndrome: how can I reduce the risk?More Patient leaflets
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