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Background The gut microbiota maturation extends beyond the first two years of life. Early perinatal and postnatal factors may influence the child’s nutritional status, which, in turn, can affect the composition of their gut microbiota. Methods This cross-sectional study characterized the gut microbiota of 84 preschool children (ages 3 to 5) from semi-urban and urban areas in Veracruz, Mexico. Fecal samples were analyzed using 16S rRNA gene sequencing. Perinatal and early-life exposures were retrieved retrospectively using a validated, interviewer-administered questionnaire, while current anthropometric measurements and dietary patterns were evaluated. Children were classified by Body Mass Index (BMI) as underweight (UW), normal weight (NW), or overweight/obese (OW). Results Clinical factors such as prematurity and early feeding showed weak associations with BMI. The dietary patterns exhibited general homogeneity, showing a Western diet with no significant changes in relation to BMI. The predominant bacterial phyla were Bacillota and Bacteroidota across all BMI groups. Alpha diversity showed significant differences according to BMI categories, while no significant differences in beta diversity, or the relative abundance of major phyla, were observed. At the family level, Prevotellaceae was more abundant in underweight children, while Lachnospiraceae was more prevalent in those with higher BMI. However, these trends were not statistically significant. The findings suggest that, within this narrow age range and shared environment, gut microbiota composition is broadly similar regardless of BMI and dietary patterns, highlighting the complexity of microbiota–host interactions in early childhood. Further studies integrating functional analyses are needed to clarify the causal links between gut microbiota and a child’s weight status.
Hernández-Rodríguez et al. (Wed,) studied this question.