Cigarette smoking as an etiologic factor in cleft lip and palate.

A case-control study has been made on smoking habits in women who, during 1975, gave birth to infants with closure defects of the central nervous system (ASB) or with cleft lip or cleft palate (CLP). For each case, two control subjects with nonmalformed infants were selected and matched for delivery unit, time of delivery, maternal age, and maternal parity. Smoking habits were routinely included in hospital records at first visit to a maternity health clinic during pregnancy. Data were studied for 66 cases of CLP, 66 cases of ASB, and 261 control subjects. Significantly more women who had infants with CLP smoked than did control women, but women with ASB infants showed a normal smoking pattern. Drug use did not explain the findings. It is suggested that maternal smoking is one of many factors of importance in the etiology of cleft lip and cleft palate in humans.