Per- and polyfluoroalkyl substances in umbilical cord serum and body mass index trajectories from birth to age 10 years: Findings from a longitudinal birth cohort (SMBCS)

Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) has been linked to low birth weight but higher childhood weight and obesity. However, little is known regarding the associations between PFAS exposure and dynamic body mass index (BMI) trajectories, particularly from birth through preadolescence.To evaluate the associations of cord serum PFAS concentrations with BMI trajectories from birth to age 10 years and longitudinal BMI in different periods.Based on 887 mother-child pairs in the longitudinal prospective birth cohort, we measured 12 PFAS congeners in cord serum and calculated BMI with anthropometric indicators at 9 follow-up time points from birth to age 10 years. The BMI trajectories were identified using group-based trajectory model (GBTM). To estimate the associations of cord serum PFAS levels with BMI trajectories and longitudinal changes in BMI, logistic regression models, linear mixed models, Bayesian kernel machine regression, and quantile-based g-computation models (QGC) were used.The median concentrations of 10 PFAS congeners included in statistical analysis ranged from 0.047 to 3.623 μg/L. Two BMI trajectory classes were identified by GBTM, characterized by high group and low group. In logistic regression models, five PFAS congeners (PFBA, PFHpA, PFHxS, PFHpS, and PFDoDA) were associated with the higher probability of being in high BMI trajectory group (odds ratio, OR: 1.21 to 1.74, p < 0.05). Meanwhile, higher PFAS mixture were related to elevated odds for the high group in both BKMR models and QGC models, with PFHpA and PFHpS being the two most important drivers jointly. In the sex-stratified analysis, the positive associations remained significant exclusively among males. In the longitudinal analysis, PFUnDA and PFDoDA were associated with increased BMI from birth to age 10 years. Furthermore, PFBS and PFHpA were negatively related to BMI throughout infancy and toddlerhood (from birth to age 3 years), whereas PFDoDA confirmed a positive association with mid-childhood (from age 6 to 10 years) BMI.Prenatal PFAS exposure was positively associated with BMI trajectories from birth to preadolescence and longitudinal BMI in various periods. Future research could use better trajectory modeling strategies to shape more complete growth trajectories and explore the relationship between BMI trajectories and adulthood health.