Longitudinal BMI-for-Age Trajectories Among Mexican School-Aged Children, 2015–2019

Background/Objectives: Childhood body mass index (BMI) is dynamic, and cross-sectional estimates do not capture within-child changes over time. This study aimed to characterize longitudinal BMI-for-age trajectories among Mexican school-aged children and examine differences according to individual and school-context characteristics.

Methods

We analyzed 463,244 children aged 5–12 years with valid anthropometric measurements over four consecutive school years (2015–2016 to 2018–2019). BMI-for-age z-scores (BAZ) were calculated using the WHO 2007 growth reference. Longitudinal patterns were identified using latent class mixed models. Multinomial logistic regression estimated the proportions of children belonging to each trajectory group, and population-averaged generalized estimating equations (GEE) examined overweight/obesity across school grades and trajectory groups.

Results