THE RELATIONSHIP BETWEEN IDIOPATHIC MENTAL-RETARDATION AND MATERNAL SMOKING DURING PREGNANCY

Objectives. Smoking has been linked to small cognitive, achievement, a nd behavioral deficits but has not been associated with more severe co gnitive impairments. This investigation evaluated the relationship bet ween maternal smoking during pregnancy and idiopathic mental retardati on (MR). Methods. Data on maternal smoking during pregnancy were obtai ned during face-to-face interviews with the mothers of 221 children wi th idiopathic MR and the mothers of 400 children attending public scho ol. All children had been born in the five-county metropolitan Atlanta area in 1975 or 1976 and were living in the area when they were 10 ye ars of age. We used exposure odds ratios (ORs) to assess the relations hip between maternal smoking and MR, controlling for sex, maternal age at delivery, race, maternal education, economic status, parity, and a lcohol use. Results. Maternal smoking during pregnancy was associated with slightly more than a 50% increase in the prevalence of idiopathic MR (adjusted OR, 1.6; 95% confidence interval, 1.0-2.4), and children whose mothers smoked at least one pack a day during pregnancy had mor e than a 75% increase in the occurrence of idiopathic MR (OR, 1.9; 95% confidence interval, 1.0-3.4). This increase was neither accounted fo r by other sociodemographic risk factors for MR nor explained by an in crease in the prevalence of low birth weight among the children of smo kers. Conclusions. Our data suggest that maternal smoking may be a pre ventable cause of mental retardation.