BMI-for-age Z-score distribution shifts among Chinese children: Gender disparity

Objective To identify gender differences among Chinese school-aged children from 1995 to 2010, and to project the future BMI-for-age Z-score distribution and prevalence of obesity. Methods The data were from four cross-sectional surveys (1995, 2000, 2005, and 2010) of Chinese National Surveys on Students Constitution and Health (CNSSCH) with a national representative sample of Chinese children, involving more than 200,000 participants at each survey. BMI-for-age Z-score distributional shifts overall and in percentiles were compared by gender. Average shift was calculated for four survey periods and used for projecting future distributions and obesity prevalence. Results BMI-for-age Z-score increased more in their upper percentile distribution, indicating that Chinese children have become heavier over the past 15 years. Gender disparity in BMI-for-age Z-score has become wider during the period. Over a 15-year period, BMI-for-age Z-score shift among girls has been stable, while boy's BMI-for-age Z-score shifts has increased linearly. By 2020, the obesity prevalence is predicted to be 10.18% and 4.99% for boys and girls, respectively. Conclusions The wider gender disparity suggested a larger proportion of obesity in boys than in girls. Therefore, gender-specific preventive guidelines and public health policies for childhood obesity and cardiovascular diseases are urgently needed in China.