Martín-Calvo N, Martínez-González MA, Segura G, et al. - Researchers examined if and how cesarean delivery (CD) is associated with offspring’s risk of overweight/obesity while adjusting for important confounders and accounting for correlations between siblings. Through online cross-sectional questionnaires, they obtained structured information from women in the ‘Seguimiento Universidad de Navarra’ cohort regarding their pregnancy history and their children’s health. Adjusted differences in BMI z-score and risk ratios (RR) were estimated for offspring’s overweight/obesity linked with CD, with hierarchical models to account for correlations between siblings. In addition, a within-family analysis was performed in 341 siblings who were discordant in delivery mode, using conditional multivariable logistic regression. Relative to children born vaginally, children born by CD exhibited higher average BMI z-scores and higher risk of overweight/obesity. Across multiple approaches to address potential residual confounding, these findings were consistent; this likely indicates a true biological effect.