IJE Advance Access published online on December 3, 2007
International Journal of Epidemiology, doi:10.1093/ije/dym239
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Parental smoking and childhood obesity—is maternal smoking in pregnancy the critical exposure?
1Institute of Social Pediatrics and Adolescent Medicine, Ludwig-Maximilian-University, Heiglhofstr. 63, 81337 Munich, Germany.
2Department of Environmental Health, Bavarian Health and Food Safety Authority, Veterinärstraße 2, 85764 Oberschleißheim, Germany.
3Division of Health and Social Care Research, Department of Public Health Sciences, King's College London, UK.
*Corresponding author. Institute of Social Pediatrics and Adolescent Medicine, Ludwig-Maximilian-University, Heiglhofstr. 63, 81377 München, Germany. E-mail: r.kriesvon{at}kinderzentrum-muenchen.de a GME Study Group: Bavarian Health and Food Safety Authority, Oberschleissheim (Gabriele Bolte, Hermann Fromme, Annette Heissenhuber, Michael Mosetter, Gabriele Morlock, Christine Mitschek, Manfred Wildner); Health Authority of the District Office of Bamberg (Winfried Strauch, Wiltrud Doerk, Rosemarie Sittig, Heidi Thamm); Health Authority of the District Office of Guenzburg (Roland Schmid, Tatjana Friess-Hesse, Gudrun Winter); Health Authority of the City Ingolstadt (Elisabeth Schneider, Traudl Tontsch, Christine Gampenrieder, Margot Motzet, Gerlinde Woelk); Department of Health and Environment, City of Munich (Brigitte Weise, Heidi Mayrhofer, Sylvia Kranebitter, Gertraud Rohrhirsch); Health Authority of the District Office of Schwandorf (Maximilian Kuehnel, Kornelia Baranek, Gitte Koch-Singer); Institute of Social Pediatrics and Adolescent Medicine, Ludwig-Maximilian-University Munich (Ruediger von Kries, Ladan Baghi); Bavarian State Ministry of the Environment, Public Health and Consumer Protection (Bernhard Liebl).
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Abstract |
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Background The concept of priming of childhood obesity by prenatal exposure to maternal smoking is based on a number of consistent studies. A recent paper found similar associations between paternal smoking and childhood obesity, questioning the presumed causal effect attributed to the prenatal exposure. Is the relation to paternal smoking consistent? Does it explain the effect of maternal smoking before or in pregnancy?
Methods Data from a cross sectional study on 5899 children in the setting of the 2005 school entrance health examinations in Bavaria were analysed. Associations between paternal smoking or maternal smoking before or in pregnancy and childhood obesity were assessed with adjustment for potential confounders.
Results The children's mean age was 5.8 years. The unadjusted odds ratio for obesity and paternal smoking was 2.0 (95% CI: 1.5, 2.6) and similar to that for maternal smoking before or in pregnancy with 2.3 (95% CI: 1.8, 3.1). After adjustment for a number of potential confounders and paternal smoking at interview the odds ratio for maternal smoking before or in pregnancy and childhood obesity was 1.9 (95% CI: 1.3, 2.7). There was no evidence for interaction between paternal smoking and maternal smoking before or in pregnancy (P = 0.38).
Conclusions Although of similar magnitude, the association of paternal smoking could only partially explain the effect of maternal smoking before or in pregnancy on childhood obesity. Whether this persistent association reflects residual confounding or causality is unclear.
Keywords Growth and development, pre-natal programming, nutritional and metabolic diseases, pre-natal nutritional physiology
Accepted 24 October 2007