Impact of the COVID-19 kindergarten closure on overweight and obesity among 3-to 7-year-old children

Background Knowledge on the impact of the temporary kindergarten closure policy under COVID-19 in 2020 on childhood overweight and obesity is inadequate. We aimed to examine differences in rates of overweight and obesity from 2018 to 2021 among kindergarten children aged 3-7 years. Methods Overweight was defined as body mass index (BMI) > 1 standard deviation (SD) for age and sex, and obesity was defined as BMI > 2 SD for age and sex. Generalized linear mixed modeling was used for analysis. Results A total of 44,884 children and 71,216 growth data points from all 57 public kindergartens in Jiading District, Shanghai, China were analyzed. The rates of obesity from 2018 to 2021 were 6.9%, 6.6%, 9.5%, and 7.3% in boys and 2.8%, 2.8%, 4.5%, and 3.1% in girls, respectively. The rates of overweight from 2018 to 2021 were 14.3%, 14.3%, 18.2%, and 15.3% in boys and 10.6%, 10.9%, 13.9%, and 11.6% in girls. The rates of obesity and overweight among kindergarten children in 2020 were significantly higher than those in 2018, 2019, and 2021. Compared to 2020, the odds ratios of the obesity rate in 2018, 2019, and 2021 were 0.67 [95% confidence interval (CI) = 0.58-0.77, P < 0.001], 0.72 (95% CI = 0.64-0.80, P < 0.001) and 0.81 (95% CI = 0.72-0.92, P = 0.001), respectively. The odds ratios of the overweight rate in 2018, 2019, and 2021 were 0.75 (95% CI = 0.69-0.82, P < 0.001), 0.78 (95% CI = 0.72-0.84, P < 0.001), and 0.89 (95% CI = 0.81-0.97, P = 0.008), respectively, compared to 2020. Conclusions The rates of overweight and obesity significantly increased among kindergarten children in 2020 after the 5-month kindergarten closure. It was critical to provide guidance to caregivers on fostering a healthy lifestyle for children at home under public health emergencies.