Some 3,400 babies under age 1 still die suddenly and unexpectedly each year. Of these, the number of infant deaths officially attributed to SIDS is probably an underestimate, experts say. In most cases, parents simply find their baby unresponsive in the crib — and autopsy practices are not standardized — so most of these heartbreaking deaths remain mysteries and are not always classified as SIDS.
“Tea [SIDS] rates have been totally stagnant” for the past 20 years, says Fern Hauck, associate professor of family medicine and public health sciences at the University of Virginia School of Medicine and a SIDS researcher. “I think it’s important that public health professionals be aware that these numbers are not going down.”
Experts say it’s important to reinforce safe sleep messages with new parents and rev up research into possible physiological factors — for example, genetics and brain abnormalities that might impair an infant’s ability to wake itself up when the child’s breathing goes awry.
The cause of some deaths are obvious—such as accidental strangulation or suffocation such as when a baby’s head has become wedged between the mattress and the side of the crib. But in most cases, the cause is unknown.
Most academic and clinical researchers still prefer the term SIDS for these infant deaths, but the US forensic medical community — coroners and medical examiners — tend to refer to them as unknown or undetermined.
Such practices have made SIDS numbers appear smaller than they are, experts say, arguing that there needs to be more consistency in the terminology to have an accurate picture. Even the Centers for Disease Control and Prevention uses graphics that include separate statistics for both SIDS and the “unknown cause” categories.
“If you just look at death certificates that say SIDS, they have gone down dramatically, but the reality is that many of the deaths that aren’t labeled SIDS would have been considered SIDS prior to 1992,” says Carl Hunt, research professor of pediatrics at the F. Edward Hébert School of Medicine of the Uniformed Services University in Bethesda, Md., and board chair of the American SIDS Institute. “They now have become part of the overall larger number of [unknown cause] deaths.”
“SIDS is underestimated,” Hauck says. “It is not vanishing. They just changed the name.”
She and others say it’s time to find new ways to reemphasize safe sleeping advice — she is creating short videos for hospitals and doctors to share with new parents, for example — and learn why some parents have stopped following it. In addition to back sleeping in a crib bare of everything but a firm mattress and the baby, experts urge parents also to avoid bed sharing and smoking during pregnancy and around the infant. Breastfeeding (with the baby always sleeping in the crib afterward), providing a pacifier (but not on a string or cord) and keeping the crib in the parents’ room are measures that seem to reduce the risk, according to the American SIDS Institute.
Even so, Hauck says, sometimes sleep-deprived parents ignore the advice.
“People make decisions in the middle of the night when the baby is screaming, and they are exhausted,” she says. “So they will take baby to bed with them or put them on their stomach because maybe they heard from a friend that this will quiet the baby. If a baby is put on their stomach for the first time, they are more likely to die. They aren’t used to being in that position, so if they get into trouble, their brain doesn’t tell them to respond properly.”
Marion Koso-Thomas, a program scientist with the Eunice Kennedy Shriver National Institute of Child Health and Human Development’s global network for women’s and children’s health research, points out that the Internet is rife with misinformation about unsafe sleep products and ineffective monitoring devices.
“We have new generations of parents who go online and see sites with new devices, such as bumpers, and they think: ‘This is cool, I’m going to try it with my baby.’ And it might not be safe,” she says. “With social media, they have a whole new world to get information from, and some of it is alarming.”
Moreover, parents may be getting advice from sources who still believe in traditional but outdated practices, she says.
“There are caregivers and grandparents where culture plays a role, and they are influencing mom’s decisions,” Koso-Thomas says, adding that pediatricians are a key source for new parents and should be assertive about doling out safe sleep information.
“We were hoping pediatricians would be among the most ardent advocates of safe sleep, but sometimes they just don’t have the time,” she says. “It’s not just that people don’t hear it, it’s that they don’t hear it from the right people.”
“A lot of parents are aware, but every generation needs to be educated,” says Michael Goodstein, division chief of newborn medicine at WellSpan Health and clinical professor of pediatrics at Pennsylvania State University. “There are grandparents who in their day were told to put their babies to sleep on their tummies, and they may be influencing the decisions parents are making.”
Beyond strengthening public messages, scientists also want to expand research into physiological factors common to SIDS infants, with the future goal of identifying vulnerable babies in advance.
“We learn more every year,” Hunt says. “We know there is a familial risk — parents who have had a baby die are at greater risk for having another. And many of the genetic studies point to the brain stem, the area of the brain that controls automatic functions, such as breathing and heart rate control [which affect] … arousal, the final protective mechanism that appears to malfunction in infants who die suddenly and unexpectedly.”
Studies already have identified genetic variants among SIDS deaths that are related to cardiac, respiratory and neurological functions, among others, as well as brain anomalies that can affect arousal. Researchers believe the cause of death comes from a failure of arousal.
“I put a healthy baby to sleep in the prone [stomach] position, and it starts to rebreathe” the air it has exhaled, says Jan-Marino (Nino) Ramirez, director of the Center for Integrative Brain Research at Seattle Children’s Hospital, who studies SIDS and brain function. “Carbon dioxide goes up and the baby starts to experience hypoxia [or insufficient oxygen]. A normal cardiorespiratory system will respond, and the baby will wake up. In SIDS, there is a malfunction in that system.”
Ramirez thinks SIDS results from the interaction of both environmental and physical factors.
“There are certain genes associated with the heart and arousal system, and the immune system, that affect the brain,” he says. “None of these genes is lethal on its own. Then some external stressor—putting the baby in a prone sleeping position—reveals the weakness. When the baby has to arouse, it can’t, and the defect becomes obvious. That’s why the ‘Back to Sleep’ campaign had an impact. The babies who didn’t have to arouse themselves survived.”
SIDS experts say that 3,400 deaths a year is still too many.
“A lot of new mothers feel ‘this can’t happen to me,’ so they may not follow all the recommendations, but it can happen to anybody,” Hauck says. “We don’t want it to happen to anybody. It’s rare. But if it happens to you, it’s 100 percent.”
She remembers an experience that occurred in 1995 when she was just starting her SIDS research. She took a call from a woman who had lost a baby to SIDS. It was the anniversary of the child’s death and the grieving mother needed to talk to someone.
“She was really struggling,” Hauck says. She recalls asking the woman when her baby had died. The answer rocked her. “She said 25 years ago,” Hauck says.
The message still haunts her today: “When you lose a baby to SIDS, it never goes away.”