April 27, 2001 - The Back-to-Sleep program has educated new parents on the importance of sleep position in preventing sudden infant death syndrome, also known as SIDS. Over the last decade, putting babies to sleep on their backs has dramatically -- but not completely -- reduced deaths from SIDS.
But many parents are not aware of the many other risk factors for SIDS. Recent reports emphasize that overheating, second-hand smoke, formula feeding, soft bedding, and bed sharing with adults may also contribute to SIDS. And like sleep position, many of these factors are preventable.
A recent CDC study finds that both breastfeeding and keeping second-hand smoke away from infants are equally important in preventing SIDS. The study of 117 SIDS cases in Louisiana over a two-year period found 55% of the deaths could have been prevented if mothers had breastfed their babies.
It's not that formula is bad, says Bradley Thach, MD, a professor of pediatrics at Washington University School of Medicine in St. Louis, who has conducted his own studies of SIDS. "It's thought that breast milk -- because it has maternal antibodies -- decreases the risk of the infant getting an infection or respiratory problem, which is a risk factor for SIDS," he tells WebMD.
The study also found that 27% of infant deaths could have been prevented if mothers had not smoked after delivery.
"Smoking [during infancy] may in some way impair the infant's ability to tolerate low oxygen levels if his head and face get covered," says Thach. Also, if the mother smokes while she is pregnant, she may be causing low birth weight and premature birth, which are also risk factors for SIDS, he says.
Thermal stress or overheating -- caused by too much clothing, heavy bedding, or a too-warm room -- can also increase the risk of SIDS, especially if a baby already has a fever, says Warren Guntheroth, MD, professor of pediatrics at the University of Washington School of Medicine in Seattle. His study appears in the April issue of Pediatrics.
"The risk of overheating is very well established in Europe, but we had seen nothing in this country about it," he tells WebMD. "After a careful survey of the world's literature, we concluded that many cases of SIDS could be explained by thermal stress."
Because a baby loses much heat through his tummy -- and even more through his face and head -- covering those areas prevents him from releasing excess heat, Guntheroth says. "The prevention then is to keep kids on their backs, don't cover their heads, don't cover them with too much of anything. And don't overheat the room."
In fact, soft bedding like pillows, mattresses, blankets, and comforters also increase risk of SIDS, says Thach. The Consumer Product Safety Commission and the American Academy of Pediatrics have issued advisories about soft bedding, he tells WebMD.
While the bedding may cause infants to overheat, or cause suffocation, a physiological process called "re-breathing" may also be at work, he says.
"Babies who get their faces in this bedding breathe their own expired air -- carbon dioxide -- and don't get sufficient fresh air," Thach tells WebMD. "This gives rise to impaired respiratory function, oxygen depletion. Some babies have not yet learned to turn their heads when oxygen gets too low, so they may not sense that carbon dioxide is building up."
Most cases of SIDS occur when babies are two or three months old, "a peak time when babies start to squirm, to pull things over their faces, develop mobility," says Thach. "Yet they have not yet learned how to extract themselves from these dangerous situations."
The SIDS Alliance advocates dressing babies in a light piece of clothing called the "Dutch sleeping sack," Thach tells WebMD. The baby's head and arms are uncovered, but the chest and rest of the body are enclosed in a "sort of a bag," he says. "Babies have a reduced ability to roll over [onto their stomach], reduced ability to scoot around in the crib and get into dangerous situations."
Allowing infants to share an adult's bed has also proven to be dangerous, causing cases of accidental suffocation, says Thach. "It appears to occur more often when adults or siblings are in bed asleep or unconscious of what is happening to the infant. Babies can pull covers over their heads, scoot under comforters. In some cases, part of the adult's body -- a leg or a breast -- covers the baby's face."
Placing babies on sofas or in overstuffed chairs is equally risky, he adds, because a baby's head can become trapped or wedged in a tight place or under cushions. "Even the bed frame is risky," says Thach.
If you have questions about SIDS, or advice for others, check out WebMD's Parenting board moderated by Steven Parker, MD.