WHO 2006 Child Growth Standards overestimate short stature and underestimate overweight in Japanese children.

Background: It is unclear whether the World Health Organization (WHO) 2006 Child Growth Standards are applicable to East Asian populations. We investigated the applicability of the WHO standards of length/height and weight to a cohort representing middle-class children in Japan. Methods: A cohort of children aged 0-5 years (3430 boys, 3025 girls) in the Tokyo Child Care Center Survey consecutively recruited from 2007 to 2013 were studied. Age- and sex-specific z-scores of length/height, weight and weight for length/height were calculated relative to either the WHO standards or the Japanese 2000 Growth References (nationally representative cross sectional survey data). Results: Compared with the WHO standards, Japanese children at birth, 1, 3, 5 years were shorter (length/height standard deviation score [SDS] -0.26, -0.82, -0.81, -0.63 for boys, and -0.15, -0.67, -0.84, -0.62 for girls, respectively) and lighter (weight SDS -0.62, -0.36, -0.34, -0.42 for boys and -0.60, -0.17, -0.29, -0.43 for girls, respectively). Weight for length/height showed smaller differences at various length/height points (SDS -0.05 to 0.15 for boys, 0.01 to 0.29 for girls, respectively). Conclusions: Adoption of the WHO standards would sub-standailyalter the prevalence of short stature, underweight and overweight in Japanese children 0-5 y cars of age. These findings advocate the use of the national references in Japan.