ABSTRACT
Background: The coronavirus disease 2019 (COVID-19) pandemic has influenced all aspects of our life since the outbreak in December 2019. The pandemic-related body mass index z-score (zBMI) and obesity prevalence changes in children have not been clearly elucidated, especially in China. Methods: Based on the Health Promotion Program for Children and Adolescents in Suzhou of China, a total of 72,175 children aged 8-12 years with complete data for four consecutive years (2017-2020), were included. zBMI and obesity prevalence were calculated. Multiple mixed linear models were used to compare the yearly changes in zBMI before (2017-2019) and during (2019-2020) the pandemic. Finding: The prevalence of obesity slightly increased from 12·29% to 13·28% from 2017 to 2019, but substantially elevated to 15·29% in 2020. The mean [95% Confidence Interval (CI)] of yearly change in zBMI before and during the pandemic were 0 ·039 (0·037, 0·042) and 0·131 (0·125, 0·138), respectively; it yielded a statistically meaningful elevation of 0·092 (95% CI: 0·087, 0·096). Meanwhile, the acceleration of zBMI change in 2019-2020 compared to pre-pandemic were more obvious in boys than in girls. Interpretation: Compared to 2017-2019, zBMI and prevalence of obesity accelerated among Chinese children during the COVID-19 pandemic. Currently, there is an urgent need to formulate effective public health policies to reduce the risk of childhood obesity resulting from the pandemic. Funding: National Natural Science Foundation of China (grant: 81602911), Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), and Gusu Health Talents Program Training Project in Suzhou, China (GSWS2020100).Declaration of Interest: The authors declare that they have no competing interests.Ethical Approval: This study was approved by the Ethics Committee of Suzhou Center for Disease Prevention and Control (No. SZJK2020-XW001).