MONDAY, March 26 (HealthDay News) -- Although the rate of Sudden Infant Death Syndrome (SIDS) dropped by more than 50 percent following the start of a U.S. campaign encouraging parents to put babies to sleep on their backs, new research suggests that risk factors other than "tummy sleeping" may explain why SIDS rates have not declined further.
Chief among those other risk factors are bed-sharing (where the baby shares a sleeping surface with a parent or parents), smoking exposure before and after birth, and having objects in the crib, the study revealed.
"It's not that there are new risk factors; it's that now not all babies are sleeping on their tummies, so other things can be uncovered," explained study co-author Felicia Trachtenberg, a senior research scientist at New England Research Institutes, in Watertown, Mass.
The findings, culled from an analysis of 568 SIDS deaths that occurred in San Diego between 1991 and 2008, appear online March 26 and in the April print issue of Pediatrics.
Tummy sleeping is still the leading risk factor for SIDS, according to study co-author Dr. Henry Krous, director of the San Diego SIDS/Sudden Unexplained Death in Childhood Research Project at Rady Children's Hospital.
Nevertheless, the Back-to-Sleep program, started in 1994, has made a huge difference.
"It has been the most successful program that one could imagine," Krous said. "The incidence rates from SIDS have dropped dramatically in the United States, and similar public educational campaigns in Western Europe and Australia and New Zealand have had similar dramatic declines."
The study found that the percentage of infants who died of SIDS who were found on their stomachs decreased from about 84 percent to 30 percent.
Certain environmental or genetic factors -- including being black, male, premature or exposed to alcohol or smoking in the uterus -- a
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