Cigarette smoking and health.

Cigarette smoking is the major preventable cause of increased mortality and premature disability in the United States. Smoking is a proven cause of coronary heart disease, chronic bronchitis and emphysema, and lung and other cancers. Maternal smoking is associated with low infant birth weight, increased perinatal mortality, and several complications of pregnancy. Passive smoking is associated with increased incidence of lower respiratory tract infections in very young children and may increase the risk of lung cancer in the nonsmoker. Smoking cessation is difficult because of nicotine addiction and psychological and social factors. Physicians and other health professions must be active both in helping people quit smoking and in preventing nonsmokers from starting. We recommend a national effort focused on preventing young people from starting to smoke.