Heatwave Exposure and Infant and Young Child Feeding Practices in Brazil: A Nationwide Study of 1.1 Million Children

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Abstract
Background: We investigated the association between short-term exposure to heatwaves and infant and young child feeding practices in Brazil.Methods: We obtained individual-level data from the Brazilian Food and Nutrition Surveillance System (SISVAN) and temperature data from the Brazilian Daily Weather Gridded Data for 2015–2022. Heatwaves were defined as periods of at least 2 consecutive days with daily mean ambient temperature above the municipality-specific 92·5th, 95th, or 97·5th percentile. Outcomes included minimum meal frequency (MMF), minimum dietary diversity (MDD), minimum acceptable diet (MAD), egg and/or flesh food consumption (EFF), sugar-sweetened beverage consumption (SwB), and unhealthy food consumption (UF). We used logistic regression combined with distributed lag non-linear models to estimate cumulative associations over 7 days.Findings: Among 1,100,321 children aged 6–23 months, heatwave exposure was consistently associated with higher odds of not meeting MAD, with estimates increasing at higher temperature thresholds: OR 1·11 (95% CI 1·07–1·14), 1·16 (1·11–1·21), and 1·24 (1·15–1·33) at the 92·5th, 95th, and 97·5th percentiles, respectively. For MMF, corresponding ORs were 1·05 (1·02–1·09), 1·09 (1·05–1·14), and 1·09 (1·01–1·17). Heatwaves were also associated with higher odds of SwB consumption and non-consumption of EFF. No consistent associations were observed for MDD or UF. Associations were more pronounced in the Northeast and in municipalities with higher material deprivation.Interpretation: Short-term exposure to heatwaves may disrupt complementary feeding practices, particularly in socially vulnerable settings. These findings may help inform public health strategies to support young children and caregivers during extreme heat events.