title: The effect of maternal smoking during pregnancy on intellectual disabilities among 8-year-old children.
abstract: Prenatal tobacco smoke exposure has been implicated as a risk factor for cognitive deficits in children. The purpose of this study is to examine the association between prenatal tobacco smoke exposure and diagnosis of intellectual disabilities (ID) among 8-year-old children living in Arkansas, Georgia, North Carolina and Utah. In 2002 and 2004, 965 ID case children were identified through a surveillance network and compared with the population of children born in the surveillance region during the same period (n = 104 607). Prenatal tobacco smoke exposure was determined from birth certificates. We estimated the effect of prenatal tobacco smoke exposure (none, <10, 10-19 and > or =20 cigarettes per day) on ID using logistic regression. Generally, the risk of ID was mildly elevated among children whose mothers smoked > or =20 cigarettes per day during pregnancy [RR 1.34; 95% (confidence interval) CI 0.96, 1.87] after adjustment for maternal education, maternal race, maternal age, marital status, child sex, birth year and study site. However, the effect of exposure to > or =20 cigarettes per day significantly differed for males [RR 1.77, 95% CI 1.20, 2.62] compared with females [RR 0.81, 95% CI 0.44, 1.50]. Supplemental analyses reveal substantial confounding of this relationship by socio-economic indicators. A differential effect of tobacco smoke exposure on the risk of ID is suggested for males and females and deserves further investigation; however, the interpretation is tempered by the potential for residual confounding.
authors.affiliation: Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7435, USA.
authors.forename: Joe M
authors.initials: JM
authors.lastname: Braun
authors.forename: Julie L
authors.initials: JL
authors.lastname: Daniels
authors.forename: Amy
authors.initials: A
authors.lastname: Kalkbrenner
authors.forename: Judith
authors.initials: J
authors.lastname: Zimmerman
authors.forename: Joyce S
authors.initials: JS
authors.lastname: Nicholas
mesh_terms: D002648:Child; D004522:Educational Status; D005260:Female; D006801:Humans; D007361:Intelligence Tests / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology / Q000523:psychology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology / Q000523:psychology*; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology