Health consequences of tobacco exposure during pregnancy and childhood.In France, about 15% of fetuses are exposed to maternal smoking during pregnancy and about 30% of children are exposed to second-hand tobacco smoke. Furthermore, 20 to 25% of young adults are active smokers. These high rates underline the persistent need for preventive actions against tobacco exposure from pregnancy through adulthood.Tobacco exposure leads to numerous deleterious consequences on physical and mental health. During pregnancy, the main adverse effects are increased risks of congenital anomalies, in utero death, preterm delivery and low birthweight for gestational age. Children exposed to tobacco before or after birth have increased risks of sudden infant death syndrome, respiratory infections and recurrent otitis media.Adolescents and adults have similar tobacco-related complications.