Effect of COVID-19 pandemic lockdowns on body mass index of primary school children from different socioeconomic backgrounds

Abstract

Childhood obesity is associated with various adverse health outcomes. Restrictive measures to contain the spread of the Coronavirus Disease 2019 (COVID-19) pandemic, like lockdowns and school closures, affected children’s daily structure, physical activity, dietary habits, and sleep quality, possibly exacerbating risk factors for childhood obesity and higher body mass index (BMI) in children. In particular, as poor socioeconomic conditions tend to favor obesogenic environments, children from lower socioeconomic backgrounds (SEBs) may have been at relatively higher risk for elevated BMI levels following pandemic measures. In this study, the impact of measures related to the COVID-19 pandemic on the BMI of third graders was investigated with regard to children’s SEB. Data from 41,728 children (8.84 ± 0.56 years, 20,431 female) were collected in the context of the longitudinal cohort study “Berlin hat Talent” and analyzed as part of the PESCov DFG project. Children were tested either before the pandemic (preCOVID: Sept2017 - March2020, n = 26,314), or following the first (post_"LD I" : Aug2020 - Dec2020, n = 6,657) or second lockdown in Germany (post_"LD II" : Aug2021 - Jan2022, n = 8,757). Demographic variables were collected via questionnaires. SEB was based on the official school type classification of the state of Berlin. Linear mixed effect models were computed to account for the hierarchical nature of the data, i.e. children (level 1) nested in schools (level 2). Outcome measures were age- and sex-adjusted BMI standard deviation scores (SDS). Independent variables were Time (preCOVID, post_"LD I" , post_"LD II" ), SEB (continuous, -2 - 2), and the interaction thereof. Covariates were Age, Gender, and Month of Test. Significant effects of Time (p < .05) and SEB (p < .001) revealed elevated BMIs in post_"LD I" and post_"LD II" compared to preCOVID cohorts and higher BMIs for children with lower SEB. A significant Time x SEB interaction (p < .01) indicated that the effect of SEB on children’s BMI increased in response to lockdowns, especially in post_"LD II" . Results suggest that the COVID-19-related measures lead to increased BMI in children, and that children of lower SEB were at particular risk for higher BMIs following lockdowns. These findings denote an alarming trend and emphasize the necessity for countermeasures to reduce lockdown-related BMI increments in children, particularly in low SEB areas. Authorities are called into action to promote physical activity of children and establish post-pandemic offers to counteract the risk of increasing rates of childhood obesity and related adverse health outcomes.