Association between parental nationalities and childhood overweight/obesity in Japan: An analysis of nationally representative survey data

Background: Few studies have investigated the association between nativity or nationality and childhood overweight/obesity in Japan. Therefore, this study aimed to assess the association between parental nationalities and childhood overweight/obesity in Japan using nationally representative survey data. Methods: Data from the Longitudinal Survey of Newborns in the 21st Century (2010 Cohort) in Japan, which longitudinally monitored height and weight of children from 2.5 years to 12 years, were used. Parental nationalities were categorized as Japanese and non-Japanese. The prevalence of overweight/obesity was calculated according to combinations of parental nationalities for each age. In addition, the generalized estimating equation was used to investigate the association between parental nationalities and overweight/obesity, and the sociodemographic characteristics of children were adjusted. Results: The analysis utilized data on 37,190 children. Results showed that the proportions of overweight/obesity in children born to non-Japanese mother and Japanese father and those whose parents were both non-Japanese were higher than the proportion in children whose parents were both Japanese regardless of age, and the proportion in children whose parents were both non-Japanese was the highest in many cases. The generalized estimating equation analysis showed that children born to non-Japanese mother had a significantly higher risk for overweight/obesity than those born to Japanese mother. Conclusions: In conclusion, the risk of childhood overweight/obesity differed based on maternal nationality in Japan. The study highlights the need for investigating health-related behaviors and statuses of non-Japanese children more in Japan in the future.