Associations of maternal employment and three-generation families with pre-school children's overweight and obesity in Japan

Backgrounds: Maternal employment has been shown to be associated with childhood overweight and obesity (Ow/Ob), but the presence of family members who care for children in place of the mothers might influence children's Ow/Ob and lifestyles. The influence of maternal employment on children's Ow/Ob should be examined together with the presence of caregivers such as grandparents. Objectives: The effects of maternal employment and the presence of grandparents on lifestyles and Ow/Ob in Japanese pre-school children were investigated. Design/Subjects: Cross-sectional study on 2114 children aged 3-6 years who attended all childcare facilities in a city and primary caregivers was conducted. Measurements: Children's weight and height, family environments (family members, maternal employment, single parent, number of siblings and parental Ow/Ob) and lifestyles (dietary, physical activity and sleeping habits) were surveyed using a self-administered questionnaire. Ow/Ob was defined by the International Obesity Task Force cut-offs. Results: The eligible participants were 1765 children. The prevalence of Ow/Ob was 8.4% in boys and 9.9% in girls. Maternal employment was associated positively with irregular mealtimes, unfixed snacking times, bedtime after 10 p.m. and nighttime sleep duration of less than 10 h, whereas three-generation families were associated negatively with irregular mealtimes after adjustment for children's characteristics and family environments. Irregular mealtimes (OR (95% CI); 2.03 (1.36, 3.06)) and nighttime sleep duration of less than 10 h (1.96 (1.28, 3.01)) were associated with increased risks of being Ow/Ob. Both maternal employment and three-generation families were significantly associated with children's Ow/Ob. However, three-generation families maintained a significant association (1.59 (1.08, 2.35)) after adjustment for maternal employment. Conclusions: These study results suggest that the grandparents who care for pre-school children in place of mothers are more likely to contribute to childhood Ow/Ob than maternal employment. The family-focused lifestyle strategies to prevent childhood Ow/Ob must include grandparents who care for children. International Journal of Obesity (2011) 35, 945-952; doi: 10.1038/ijo.2011.82; published online 26 April 2011