It wasn’t long ago that nearly 10,000 infant children died each year from unknown causes in the United States. Even now the phenomenon, still known as “Sudden Infant Death Syndrome” or SIDS, remains baffling to doctors.
But thanks to a nationwide publicity campaign that began some two decades ago, SIDS deaths are down more than 50%. Many parents have learned to avoid the most glaring risks – laying their children down on their stomachs to sleep, or placing too many loose blankets or pieces of clothing in their child’s crib.
Yet SIDS persists, largely because no single factor seems to explain how perfectly healthy babies can be alive and smiling at their bedtime but then expire without obvious warning or sign of distress, often by the next morning.
Accidental suffocation was long thought to be the primary cause. Some parents or their child’s caretaker mistakenly believed that a child might choke on its own vomit if it were placed on its back to sleep. In fact, the real risk was having its face buried in the soft bottom of its crib, leaving it unable to breathe. Children could also crawl under the covers of a blanket unable to escape, fatally limiting their oxygen intake during sleep.
About half of all SIDS deaths are thought to happen this way. That may be why the 1990s SIDS campaign, called “Back to Sleep,” was able to reduce the mortality rate by about the same percentage. But it hasn’t solved the riddle of SIDS. In fact, in polls, a shockingly high number of parents, especially African-Americans and Native Americans, still say they believe that children are safer sleeping on their stomachs – largely due to folk wisdom or inherited child-rearing practices. If those parents are still engaged in risky infant sleep practices, why do such a small percentage of their children die from SIDS?
The obvious answer is that other factors are at play – it’s just not clear what they are. For example, SIDS deaths are more likely to occur in colder climates, possibly due to a mild cold or upper respiratory infection occurring in infants with weakened immune systems. Nervous system dysfunction – either in the brain stem or in more peripheral areas — may also be a factor, as well as an abnormally large brain size (not resulting from simple edema or cerebral abnormalities). Maternal diet, vitamins, and breastfeeding have also been investigated and some degree of correlation has been found in each case.
In the end though, these explanations still largely amount to just medical speculation. Despite a spate of scientific studies, doctors are really no closer to understanding with certainty why SIDS appears when it does, and therefore, what preventative measures, besides sleep position, can reduce mortality.
However, a breakthrough of sorts may be on the horizon. In October 2017, researchers at the University of Adelaide found strong evidence of a link between SIDS deaths and abnormalities in brain transmitters in infant boys born prematurely. The brain transmitters which control neck movements and breathing were found to be unusually weak in a subset of cases which could explain why some male babies sleeping on their stomachs are unable to respond to breathing challenges by adjusting their head position, and instead, suffocate.
The sample of cases tested – just 55 – was small, but the correlation found was stronger than any previously tested for. It’s a small breakthrough, but it demonstrates clearly that certain classes of babies – male “preemies” – are more vulnerable.
What can be done? Not much, at present. The interaction of chemicals that leads to the specific neurotransmitter vulnerabilities detected is complex. Not all male infants, even those born prematurely, are vulnerable Future research is needed to develop the screening techniques or biomarkers to identify the infants who may be specifically at risk of SIDS.
It’s a start, though, and offers hope to parents that suffer one of the most devastating guilt-inducing losses imaginable – sometimes blaming themselves but in the end not really knowing what, if anything, they might have done to prevent it.