^*Department of Health Sciences, School of Medicine, University of Yamanashi, Yamanashi, Japan

Correspondence: Zentaro Yamagata Department of Health Sciences, School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan. E-mail: zenymgt@yamanashi.ac.jp

^**The costs of publication of this article were defrayed, in part, by the payment of page charges. This article must, therefore, be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Received 27 June 2006; Accepted 1 May 2007.

Abstract

Objective: To examine the extent to which maternal smoking during early pregnancy and other prepregnancy lifestyle habits are associated with obesity and overweight in 5-year-old Japanese children.

Research Method and Procedures: We studied 1417 mother-child pairs enrolled in Project Enzan—a prospective cohort study. The dependent variables, childhood overweight and obesity, were defined with an international cut-off value. Maternal smoking during early pregnancy and other prepregnancy lifestyle habits were used as independent variables.

Results: Maternal smoking habits were associated with overweight in the 5-year-old children [ adjusted odds ratio (OR): 2.15; 95% confidence interval (CI): 1.12 to 4.11] . Maternal sleep duration of 8 h/d negatively affected childhood overweight (adjusted OR: 0.71; 95% CI: 0.49 to 1.04). Children whose mothers skipped breakfast were likely to become overweight (adjusted OR: 1.78; 95% CI: 1.14 to 2.77). The results of childhood obesity analysis were similar to those of childhood overweight analysis.

Discussion: The results of this study suggest that there are effects of smoking during early pregnancy and other maternal lifestyle habits on the onset of childhood obesity in Japan. Therefore, interventions in maternal lifestyle habits are required to prevent childhood obesity, and these interventions should be initiated before pregnancy.