What Causes SIDS
As most parents know, SIDS is the unexplained death of an infant younger than 1 year. Babies who are younger than 6 months -- when 90 percent of SIDS deaths occur -- are particularly vulnerable. And even though the back-to-sleep campaign of more than a decade ago has decreased the incidence of SIDS deaths by more than 50 percent, SIDS remains the number one cause of infant death in the United States. In fact, some 2,500 babies die from SIDS every year in this country, according to the National Institutes of Health.
What is especially troubling to experts is that no one really knows what causes it. "Most babies who die of SIDS appear perfectly normal," says Rachel Moon, MD, a pediatrician at Children's National Medical Center, in Washington, D.C., and a member of the AAP's SIDS Task Force. There is some speculation that babies who die of SIDS have an abnormality in the neural network that controls blood pressure, breathing, and temperature regulation, she explains. Or these babies may not produce adequate serotonin, a brain chemical that transmits nerve impulses that would cause a baby who wasn't getting enough oxygen to wake up.
"We do know that there are demographic and environmental risks," Dr. Moon says, noting that African-American and Native American babies die of SIDS at two to three times the national average, for example, and babies who are born to women who smoked during pregnancy or to very young women are at a higher risk. Preterm and low birth weight infants are also at higher risk. "But no baby is absolutely safe from SIDS," says John Kattwinkel, MD, chair of the AAP's SIDS Task Force.
What worries experts are parents like Stacy Ruskuski, of Brick, New Jersey, who weigh the odds and decide that because they don't fall into any of the high-risk categories, their babies will be safe sleeping on their stomach or side. "We tried putting our baby on his back for the first three or four weeks, but he would just cry and cry," Ruskuski says. After that, she put her son down on his stomach and he started sleeping contentedly -- by 3 months, he slept for 10 hours a night. However, this solution is risky: According to the American SIDS Institute, babies who sleep on their tummy have almost 13 times the risk of death as babies who sleep on their back.
Indeed, babies do sleep more soundly on their tummy, says Dr. Moon, which may prevent them from awakening when they're not getting enough oxygen, or it may allow them to re-breathe too much carbon monoxide, which can be deadly. Parents who fear that a baby who sleeps on her back is more susceptible to aspirating vomit need not worry. "That virtually never happens," says Dr. Moon, "and in fact, babies who sleep on their stomach are much more likely to choke on vomit than babies who sleep on their back."