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. Klonoff-Cohen, an assistant professor of family and preventive medicine at the University of California, San Diego.
The study was published Tuesday in The Journal of the American Medical Association.
"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. Schoen-dorf, 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 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 SIDS Alliance, a nonprofit 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."