"The first few times babies who usually sleep on their backs or sides shift to the prone (lying face down) position, they have a 19-fold increased risk of sudden death," says senior author Bradley T. Thach, M.D., a Washington University pediatrician at St. Louis Children's Hospital. "We wondered if these babies, finding themselves face down, 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?"
Thach and his colleagues studied 38 healthy infants aged 3 to 37 weeks. Half of the babies usually slept prone or had a history of turning prone during sleep. The other babies had never slept prone. The study is reported in the December issue of the journal Pediatrics.
The researchers constructed a moderately asphyxiating surface, a comforter placed over a foam rubber mattress with a two-inch deep circular depression that would lie directly beneath the baby's face. When babies sleep face down on the surface, they "rebreath" air they have exhaled, and this air can have high amounts of carbon dioxide. A catheter taped beneath the babies' noses allowed monitoring of carbon dioxide levels.
After four to five minutes of sleeping face down on this surface all 38 babies awoke and attempted to get fresher air. The babies with experience sleeping prone generally lifted and turned their heads to either side when they sensed the air was stale, thereby increasing their supply of oxygen-rich air. In contrast, the inexperienced infants generally nuzzled the bedding or briefly lifted their heads and then resumed sleeping face down. Overall
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Contact: Gwen Ericson
ericsong@wustl.edu
314-286-0141
Washington University School of Medicine
6-Dec-2004