Maternal Overweight and Obesity Alter Neurodevelopmental Trajectories During the First Year of Life: Findings from the OBESO Cohort.

Background/Objectives: Overweight and obesity during pregnancy are metabolic risk factors that may compromise offspring brain development. The first 1000 days of life represent a critical window in which neurodevelopmental trajectories are shaped by intrauterine and early-life exposures. The 6- and 12-month milestones are key checkpoints where deviations may emerge, and interventions are most effective. This study evaluated the association between maternal pregestational weight status and infant neurodevelopment at 6 and 12 months of age. Methods: Mother and infant pairs from the OBESO perinatal cohort in Mexico City were included. Women in the first trimester of pregnancy were classified as normal weight and overweight/obesity according to their pregestational body mass index (pBMI), calculated from self-reported pre-pregnancy weight. Infant neurodevelopment was assessed at 6 and 12 months using the Bayley Scales of Infant Development III, Third Edition (BSID-III). Descriptive, bivariate and multiple linear regression analyses with mixed effects correction were conducted. Results: Among 97 mother-infant pairs, infants of mothers with overweight/obesity had lower language and socio-emotional scores at 12 months. Higher maternal pBMI was correlated with lower motor scores at 6 and 12 months, and with lower language scores at 12 months. Longitudinal analysis showed that maternal overweight/obesity was associated with a significant decline in language development from 6 to 12 months. (p = 0.002). Conclusions: Maternal pregestational overweight or obesity may negatively influence early neurodevelopment, particularly affecting language and cognitive domains during the first year of life. These early deficits could reflect alterations in intrauterine programming associated with maternal metabolic status.