Cigarette smoking as a risk factor for sudden infant death syndrome: a population-based study

Sudden infant death syndrome (SIDS) is the unexplained death of a healthy infant, often during sleep. The cause of SIDS is not known and methods to prevent or predict SIDS have not been discovered. The most common age for SIDS is from one to six months. The rate of sudden infant death has doubled in Sweden since the 1970s, even as the overall infant mortality rate dropped by nearly 40 percent. Risk factors for SIDS were evaluated for a group of 279,938 infants born in Sweden between 1983 and 1985; the group included all infants who survived the first week of life. SIDS occurred in 7 per 10,000 babies for the entire group. Higher rates of SIDS were found if the mother was young, had more than one child, smoked cigarettes, and if the infant was male. Maternal smoking doubled the risk of SIDS, and the more the mother smoked, the greater the risk. The age at which infants died was apparently related to the mother's smoking as well; babies of smokers died younger. In Sweden and other similar countries, maternal smoking may be the most significant, preventable risk factor for SIDS. The number of infants who die from sudden infant death syndrome in Sweden could be reduced by 27 percent if all mothers did not smoke.