Canadian coroners are increasingly staying away from listing SIDS, or sudden infant death syndrome, as the cause of death when an infant dies unexpectedly. Because SIDS lacks a single identifiable cause or a diagnostic test to confirm the diagnosis, coroners are increasingly classifying deaths that otherwise would have been listed as due to SIDS under other classifications. The result is that some Canadian parents are confused about what SIDS is, what these other more recent terms mean, and how to best keep babies safe.
"Sudden Infant Death Syndrome (SIDS) is the cause assigned to infant deaths that cannot be explained after a thorough case investigation including death scene investigation, autopsy, and review of the clinical history,” explains Dr. Jeffrey Colvin, pediatrician and researcher at Children’s Mercy Kansas City. Our definition of SIDS hasn’t changed significantly since the 1990s, when SIDS deaths got widespread media attention, but the medical community has become more concise about using the diagnosis, Colvin tells HuffPost Canada.
No matter how it is classified on the death certificate, the seemingly unexplained passing of an otherwise healthy infant is a terrible nightmare come to life for parents. But as researchers and medical professionals learn more about SIDS, and related causes of death, they also learn more about which babies are most at risk, and how it can be prevented. And while unfortunately not every infant’s unexplained death is preventable, the good news is that many of them are.
Read on to learn more about SIDS and related conditions, including which babies are most at risk and how such deaths can be prevented.
How often does SIDS occur? In the United States there are approximately 40 SIDS deaths for every 100,000 live births, Colvin says, and SIDS is the leading cause of death in infancy (children less than 12 months old) after the age of one month. It’s hard to determine how many SIDS deaths there are in Canada because provinces categorize these deaths differently. From 2003-2007, when most provinces still used the SIDS classification, it accounted for 6 per cent of infant deaths in Canada or about 30 per 100,000.
What is SUID? SUID stands for Sudden Unexpected Infant Death. It is sometimes diagnosed as the cause of death for infants who die from causes that could be explained or unexplained. "SUID deaths do not necessarily have to occur during sleep,” Colvin says. "SUID would include the sub-categories of SIDS, ASSB, and Unknown, but also includes accidental ingestions, etc."
How often does SUID occur? SUID is more commonly reported than SIDS — in the U.S. it accounts for 193 deaths per 100,000 live births in infants. Not all provinces use this classification, or use both it and SIDS, so the number is hard to quantify for Canada.
What is ASSB? ASSB is another cause of death that may previously have been described as SIDS but is now being used for infant deaths with this particular cause. ASSD stands for Accidental Suffocation and Strangulation in Bed.
How can these deaths be prevented? There is a focus on three overlapping categories of risk factors, Colvin explains: the infant’s age/critical development period, an infant’s vulnerability (for example, a cardiovascular or pulmonary condition specific to that infant), and exogenous stressors.
Is age a factor? By definition SIDS and SUID apply to infants, which means children under 12 months of age. The peak age for SIDS deaths is 1-4 months, and 90 per cent of SIDS deaths occur before six months of age.
What are exogenous stressors? Exogenous or external factors are ones that don’t have to do with the infant specifically but are related to the baby’s surrounding environment. For SIDS and SUID this can include factors like sleep position, bedding, bed sharing, and exposure to tobacco smoke.
Are there other risk factors? About 60 per cent of SIDS-classified deaths occur in boys, and they happen more commonly in the fall and winter. Babies born prematurely or at low weights also have a higher risk of dying of SIDS.
Why have the rates for these conditions changed in recent decades? There are a variety of factors that might be affecting the number of SIDS, SUID, and ASSB diagnoses for causes of death in recent years, Colvin explains. With the widespread media attention on SIDS deaths in the 1990s also came more knowledge about it, and about the ways it can be prevented. Smoking in the home is a risk factor for SIDS, and smoking rates have continued to decline since the 1990s as well. “Although the combined rates of SIDS, Unknown, and Accidental Suffocation and Strangulation in Bed have been relatively stable since the mid-to-late 1990s, the rates of ASSB have increased and the rates of SIDS have decreased,” Colvin says.
How are these unexpected deaths classified in Canada? That depends on where you live. Ontario, Newfoundland and Labrador, and Quebec still use SIDS, for example; Alberta has used “undetermined” since 2013; Manitoba began using SUID in 2010.
How can parents prevent SIDS? "Parents can reduce the risk of SIDS and other causes of sleep-related death in their infant by practicing the A-B-C’s of safe sleep: Alone, on their Back, and in a Crib,” Colvin says. It’s recommended that infants sleep alone in a crib or bassinet, with no bed sharing with adults or objects like blankets and toys, he says, though there’s evidence to support sharing a room on a different sleeping surface.