Infants in households where people smoke are more than twice as likely to die of sudden infant death syndrome as those in smoke-free environments, a new study said.
The study is confirmation of earlier research suggesting that infants who breathe secondhand smoke face an increased risk of SIDS, even if their mothers quit smoking during pregnancy.
The greater the number of smokers or the greater the number of cigarettes an infant is exposed to, the higher the SIDS risk, said the study’s lead author, Hillary S. KlonoffCohen, an assistant professor of family and preventive medicine at the University of California, San Diego.
“It’s not enough for a woman to stop smoking while she’s pregnant. It’s important that she doesn’t start up again after the birth of her child,” said Dr. Kenneth C. Schoendorf, a SIDS researcher with the National Center for Health Statistics in Hyattsville, Md.
“It’s also important that other people not smoke around the infant,” said Schoendorf, who wasn’t involved in the study.
SIDS is the sudden, unexpected death of an apparently healthy infant that remains unexplained after an autopsy and thorough investigation. It is the most common cause of death in the Western world of infants between 1 month and 1 year old, killing about 6,000 U.S. babies a year.
The study, published in today’s issue of The Journal of the American Medical Association, should be of significant interest in Washington state, where one in four infant deaths is attributed to SIDS, according to Jeff Collins, a Spokane doctor.
In Spokane County, 13 infants died of SIDS in 1993. Of the 495 Washington infants who died that year, 139 died of SIDS.
The researchers interviewed parents of 200 infants who died of SIDS in Southern California between January 1989 and December 1992, and parents of 200 similar healthy infants.
The infant was 3.46 times more likely to die if only the father smoked; 2.28 times more likely if only the mother smoked; and 2.18 times more likely if a live-in adult other than a parent was the only smoker, the researchers said.
If more than one adult smoked, the risk of the infant dying was 3.5 times higher than for infants in smoke-free households, the researchers said.
Smoking in the same room as an infant pushed the risk even higher, the researchers said.
Klonoff-Cohen said she didn’t know why the rate was highest when only the father smoked.
The SIDS Alliance, a non-profit educational organization based in Columbia, Md., said the study doesn’t suggest smoke exposure alone causes SIDS, but smoke apparently poses “an increased challenge to a baby who is already vulnerable.”
In the same study, the position in which babies were laid to sleep appeared not to matter in SIDS risk, contrary to numerous other studies, most done outside the United States. Klonoff-Cohen said more U.S. research is needed to resolve the question.
In the meantime, parents should continue to lay infants down to sleep on their sides or backs instead of on their stomachs, said the SIDS Alliance and other experts.