BALTIMORE - For infants, cold weather brings a counter-intuitive danger - overheating.

Johns Hopkins Medicine issued a warning Wednesday that infants who are bundled too tightly against the cold could be at greater risk for sudden infant death syndrome, or SIDS.

Heavy blankets, hats and clothing can cause infants to overheat, which is one of the risk factors for SIDS - the leading cause of death of children under age one.

"It's fine to swaddle a baby, but people will tend to over-wrap infants in cold weather, even if their house is warm," said Dr. Ann C. Halbower, medical director of the Johns Hopkins pediatric sleep disorders program. "Too many blankets, especially if the head is covered, can lead to a problem where the infant just can't vent."

Halbower warned against covering a baby's head or face, the areas of the body where the most heat is released. She said blankets should come up just to a baby's armpits and should be tucked tightly into the bottom of the bed to prevent the child from scooting further under the covers.

"If an infant is notably sweating," she said, "the baby should be unwrapped and dressed much lighter."

She added that babies should sleep on their backs if possible and not in the same bed as other people, which puts them at greater risk of overheating and suffocation. Babies under six months of age and those born prematurely are particularly vulnerable.

Other risk factors for SIDS include exposure to cigarette smoke, loose bedding and soft-sleeping surfaces, such as sofas and waterbeds.

The Centers for Disease Control and Prevention defines SIDS as the sudden death of an infant under one year of age that cannot be explained by a thorough investigation. More than 2,000 infant deaths are attributed each year to SIDS in the United States.

Distributed by the Los Angeles Times-Washington Post News Service=