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Some Babies at Greater Risk for SIDS

Those lacking experience sleeping on stomachs more prone

FRIDAY, Dec. 10, 2004 (HealthDayNews) -- A baby's lack of experience sleeping on his or her stomach may be linked to an increased risk of sudden infant death syndrome (SIDS), a new study claims.

The study, conducted by researchers at Washington University School of Medicine in St. Louis, concluded that babies who never sleep on their stomachs don't learn behaviors that reduce their risk of SIDS. The findings appear in the December issue of Pediatrics.

"The first few times babies who usually sleep on their backs or sides shift to the prone (lying facedown) position, they have a 19-fold increased risk of sudden death," senior author and pediatrician Dr. Bradley T. Thach said in a prepared statement. "We wondered if these babies, finding themselves facedown, fail to turn their heads to breathe easier. If so, is that because their reflexes haven't developed far enough or because they just don't wake up?"

When babies sleep facedown, they can re-breathe air that they've exhaled. This air can contain high levels of carbon dioxide.

Thach and his fellow researchers studied 38 healthy babies aged 3 weeks to 37 weeks. Half of the babies usually slept on their stomachs or turned onto their stomachs during sleep. The other babies had never slept on their stomachs.

For the study, all the babies were placed on their stomachs to sleep and observed by the researchers. After about five minutes of sleeping facedown, all the babies woke up and tried to get fresh air. The babies who had experience sleeping face down lifted and turned their heads to either side, enabling them to increase their supply of fresh air.

But the babies with no experience sleeping on their stomachs nuzzled the bedding or only briefly lifted their heads, and then resumed sleeping facedown, which meant they didn't get much fresh air.

The researchers said their results suggest that babies learn through experience which head movements help reduce the discomfort of breathing high levels of carbon dioxide and avoid conditions that may trigger SIDS.

But Thach said a baby's ability to lift his or her head while lying prone may not be enough to protect against SIDS.

"Many parents think that if a baby can lift its head, he or she is OK to sleep prone, but that is a false assurance. Parents and other caregivers should never place an infant in the prone position until he or she shows the ability to spontaneously turn all the way over. Back-sleeping should continue to be strongly encouraged to protect against SIDS," he said.

More information

The Nemours Foundation has more about SIDS.

SOURCE: Washington University School of Medicine, news release, Dec. 6, 2004
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