Sudden infant death syndrome, or SIDS, kills about 2,500 babies each year in the United States, most often those who are between two- and four-months-old.

Babies put to bed on their stomach and side, especially with blankets and pillows, or those who share a bed with their parents, are known to be at extra risk of SIDS, also known as "crib death."

So doctors and public health officials tried to get the message to parents that infants should be put to sleep on their back on a firm surface, starting in 1994 with the "Back-to-Sleep" campaign. Parts of the message, however, still haven't gotten through, researchers at the University of California, San Diego School of Medicine found.

"Far and away, the safest sleep environment for a baby is to be placed in a crib with a well-fitting mattress, the mattress is firm, there are no soft objects in the bed - no bumper pads, no blankets, no overstuffed toys - and the baby in the crib is sleeping alone," said Henry Krous, who worked on the study.

"When caretakers put an infant down to sleep, they shouldn't just think about putting a baby on its back, they should think about these other risk factors."

Krous and his colleagues compared the cases of all babies who came through the San Diego medical examiner's office with SIDS as the cause of death between 1991 and 2008, a total of 568 infants.

They found that fewer babies died suddenly after the word got out about dangerous sleeping positions. About one in 750 babies were killed by SIDS in 1991, compared to one in 1,600 in 2008. Most of that drop came in the decade after the campaign began, and the number dying has stabilized in recent years.

The study team also noticed there were still preventable risks involved in most recent SIDS cases.

The number of infants who'd been put to sleep on their stomach, for example, fell from 85 percent before the campaign to 30 percent afterwards, but the number found deceased in an adult bed increased from 23 percent to 45 percent.

"People are getting part of the message, but not all of it," said Debra Weese-Mayer, a pediatrician at the Northwestern University Feinberg School of Medicine in Chicago, who wasn't involved in the study.

Most of the babies who died since 1991 had at least one innate risk for SIDS, such as being a boy or African American or being born prematurely. Infants were also more at risk if their mothers smoked or drank alcohol.

Krous told Reuters Health that "the best of both worlds" is to let the baby sleep on a separate surface immediately next to the parents' bed. Keeping the mother and baby close promotes breastfeeding, but avoiding bed-sharing cuts the SIDS risk.

Weese-Mayer said she thinks preventable risks haven't been eliminated for multiple reasons: because some parents never learn about the dangers of stomach sleeping or sharing beds and because others know the risks but choose alternative sleeping positions anyway.

"What's sad is, because the (decreased number of deaths) has suggested to people that SIDS is going away, it decreases the public visibility of SIDS, and there couldn't be anything farther from the truth - it's not going away," she said. SOURCE: bit.ly/H52vcp

(Reporting from New York by Genevra Pittman at Reuters Health; editing by Elaine Lies and Bob Tourtellotte)

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