Background: Although many epidemiological studies have shown an association between maternal smoking during pregnancy and offspring overweight, it is still under debate whether intrauterine tobacco smoke exposure directly affects offspring obesity or if the association is rather due to confounding by lifestyle factors.
Objectives: The association of parental smoking habits at pre- and post-natal periods with offspring body mass index (BMI) was investigated, whereas maternal smoking during pregnancy was validated by cord serum cotinine measurements.
Methods: Multivariable linear regression analysis, based on the German Ulm Birth Cohort Study of 1045 children born in 2000 with annual/biennial follow-up until the age of 8 years (n = 609), was conducted.
Results: BMI of offspring from mothers who smoked during pregnancy and non-smoking mothers differed significantly at 8 years. Maternal smoking during pregnancy was associated with an increase in BMI of 0.73 kg m(-2) [95% confidence interval: 0.21-1.25] in 8-year-old children after adjustment for multiple potential confounding variables. Both pre- and post-natal smoking of fathers (0.34 [0.01-0.66]/0.45 [0.08-0.81]) and of both parents (1.03 [0.43-1.63]/0.56 [0.14-0.98]) were likewise significantly associated with offspring BMI.
Conclusions: The observed patterns suggest that residual confounding by living conditions in smoking families rather than specific intrauterine exposure to tobacco smoke may account for the increased risk of offspring overweight.
Keywords: Body mass index; cotinine; pregnancy; smoking.
© 2013 The Authors. Pediatric Obesity © 2013 International Association for the Study of Obesity.