|Sudden Infant Death Syndrome in Canada||Return to MCH Theme page|
3. Additional Information:
Sudden infant death syndrome (SIDS, also known as crib death or cot death) is the leading cause of death for infants between 28 days and one year (i.e., post-neonatal deaths). It refers to the sudden and unexpected death of an apparently healthy infant aged under one year which cannot be explained after all known and possible causes have been ruled out through autopsy, death scene investigation and review of the medical history.
In 1996, there were 2,051 reported infant deaths in Canada (i.e., live born children who died less than one year old). 168 (8.2%) were attributed to SIDS. The SIDS deaths were the commonest cause of post-neonatal deaths (28 days to one year) where they formed 26%, followed by birth defects.
The SIDS rate has been steadily declining, from 1.2 per 1,000 live births (1980), to 0.5 per thousand in 1996 (i.e., 1 in 2,000 births). Canada lies below Australia (0.9 per 1,000), the USA (0.8) and Britain (0.75). Japan has a rate of 0.4 and, as usual, the Netherlands seems to have the lowest rate at 0.25 per 1,000 live births. It's not clear why the decline has occurred, but maybe the widespread public awareness is influential.
SIDS rates are roughly three times higher in Aboriginal populations than the national rate.
Etiology remains surprisingly unclear. The following risk factors have been identified (and new theories seem to appear regularly). See SIDS Canada web site.
Please Note: risk factors may not be actual causes - they are factors found to be associated with SIDS.
- risk higher among males, and in lower socioeconomic groups
- teen age mothers, and those receiving less pre-natal care
- pre-term and low birth-weight infants
- risk higher when children sleep on their fronts (prone) than on their back (supine) (risk 6.6 times higher)
- maternal smoking during pregnancy seems to increase the risk about 3 times. Exposure to second-hand smoke doubles the risk; substance abuse during pregnancy is also associated with risk.
- risk is greater if the infant's head becomes covered during sleep; overheated bedroom and cluttered sleeping area seem to be linked
- breast feeding is protective (but this may be confounded by the other risk factors)
Theories of etiology include an interaction of risk factors with varying probabilities; a "triple risk" hypothesis consisting of general vulnerability, age-specific risks and precipitating factors (Wedgwood, 1972). Filiano & Kinney (1994) presented another triple risk model that included prenatal injury of the brainstem, perhaps including astrogliosis. Several authors have posited hypoxia as a mechanism, but others dissent. (For a review of etiological theories, see WG Guntheroth & PS Spiers. The triple risk hypothesis in sudden infant death syndrome. Pediatrics 2002;110:e64)
Assigning SIDS as the cause of death is the responsibility of the local medical examiner.
Further information: Canadian Perinatal Surveillance System
Updated January 13, 2015