Maternal cigarette smoking and oral clefts: a population-based study.

Abstract
Analyses of 1984 data from the Maryland Birth Defects Reporting and Information System indicate that mothers of infants with oral clefts (cleft lip with or without cleft palate; and cleft palate) smoked more during pregnancy than mothers of infants with other defects (odds ratio OR of 2.56 and 2.39, respectively). There was a dose-response relation between the daily amount smoked and the risk of clefting. Adjustment for available confounding variables did not account for the association between smoking and oral clefts.