Experts hypothesized increased weight gain in children associated with the COVID-19 pandemic, potentially due to closures of schools and recreational facilities with consequent reduction of physical activity and dietary changes. Our objective was to evaluate whether the rate of change of child BMI increased during the COVID-19 pandemic compared to pre-pandemic years.


The study population of 1996 children ages 2-19 years with at least one BMI measure before and during the COVID-19 pandemic was drawn from 38 pediatric cohorts across the US participating in the ECHO-wide Cohort Study. We modelled change in BMI using linear mixed models adjusting for age, sex, race, ethnicity, maternal education, income, baseline BMI category, and type of BMI measure. Data collection and analysis was approved by the local IRB of each institution or by the central ECHO IRB.


BMI increased during the COVID-19 pandemic compared to previous years (0.24 higher annual gain in BMI during the pandemic compared to previous years, 95% CI 0.02, 0.45). Children with BMI in the obese range compared to the healthy weight range were at higher risk for excess BMI gain during the pandemic, while children in higher-income households were at decreased risk of BMI gain.


One effect of the COVID-19 pandemic is an increase in annual BMI gain during the COVID-19 pandemic compared with the three prior years among children in our national cohort. This increased risk among US children may worsen a critical threat to public health and health equity.

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Competing Interests

CONFLICT OF INTEREST DISCLOSURES: The authors have no conflicts of interest relevant to this article to disclose.