Some deaths that are originally thought to be SIDS actually turn out to be the result of other conditions such as meningitis, encephalitis, and overlooked congenital or metabolic problems.
Although the actual cause of SIDS deaths remains unexplained, the search for a cause continues. It is not clear whether a single cause for all SIDS deaths will emerge. Below are various clues and possible triggers that researchers have identified.
Some cases of SIDS may occur due to the baby sleeping on their side, or face-down on their stomach. The Canadian Paediatric Society, the Canadian Foundation for the Study of Infant Deaths, Baby’s Breath (formerly known as the Canadian Institute of Child Health, and Health Canada) all recommend that normal, healthy babies should be placed on their back for sleep. Parents should give their baby some carefully supervised “tummy time” several times each day while the baby is awake. This can help prevent “flat head” and counteract any effects of back sleeping on muscle development.
Poor temperature control
Some infants may have poor temperature control. It used to be that the majority of SIDS deaths occurred in winter, possibly due to babies being over-wrapped in clothes and at risk of becoming overheated. Now, there is evidence showing no difference in the number of SIDS deaths associated with different seasons. However, overheating is still considered a risk for SIDS.
Central nervous system abnormalities
Although SIDS babies may appear to be in perfectly good health, they may have an abnormality of the central nervous system (brain, nerves, or spinal cord) that has yet to be identified. For example, some infants may have underdeveloped parts of their central nervous systems that are not yet mature.
Flawed breathing control
Affected babies may have some flaw in their breathing control or ability. Research has shown that some babies may have borderline breathing abnormalities that may be the result of delayed maturation of the part of the central nervous system that controls breathing.
Exposure to tobacco smoke
Exposure to smoke is a health risk for unborn babies and for growing babies. Exposure to smoke has been identified as one of the great risk factors for SIDS.
Possible risk factors for SIDS include:
- prone sleeping position (e.g., on stomach or side)
- pre-term (premature) birth or low birth weight
- slower-than-normal growth rate
- sleeping on a soft surface
- sleeping in an area that is too warm
- smoking or drug use during pregnancy
- sleeping in a car seat or other device (swing, stroller, etc.)
- socio-economically disadvantaged background
- First Nations or African descent
- cluttered sleeping area (e.g., toys, pillows, blankets in the crib)
- sharing a bed with another child
- parents who are smokers
- a brother or sister who has died of SIDS
- young mother
- late or no prenatal care
- being male
- sharing a bed with the baby
- a history of needing resuscitation because breathing has stopped
- low Apgar score at birth (An Apgar score measures a baby's overall condition and is taken soon after a baby is born. It is based on the baby's skin colour, breathing, heart rate, responsiveness, and muscle tone.)
Profiles of mothers of babies who die of SIDS show that problems during pregnancy may predispose their babies to the syndrome. For example, mothers who smoke, are anemic, or are undernourished appear to have babies who are at higher risk for SIDS.