PFAS were measured in mid-pregnancy serum collected from 539 study participants.

We evaluated associations of five PFAS with four gestational weight gain outcomes.

PFHxS and PFOS were associated with greater GWG and GWG z-score.

PFHxS and PFOS were associated with greater odds of excessive weight gain.

Pre-pregnancy BMI may modify the impact of PFAS on weight gain in pregnancy.

Per- and polyfluoroalkyl substances (PFAS) are widespread and persistent contaminants detected in most humans. PFAS exposure has been linked to adverse health conditions, including excessive gestational weight gain (GWG), though results have been inconsistent.

Participants (n = 539) were enrolled in the Healthy Start Study, a Colorado-based cohort (2009–2014). Eleven PFAS were measured in serum collected during pregnancy (median 27 weeks of gestation). GWG was quantified in four ways: absolute change in weight during pregnancy; GWG adjusted for the duration of pregnancy (z-score); 3rd trimester rate of weight gain; and categories of recommended GWG according to Institute of Medicine (IOM) guidelines. PFAS detectable in >60 % of samples (perfluorohexane sulfonate [PFHxS], perfluorooctane sulfonate [PFOS], perfluorooctanoate [PFOA], perfluorononanoate [PFNA], and perfluorodecanoate [PFDA]) were analyzed. We fit covariate-adjusted general linear models for continuous outcomes and multinomial logistic regression models for the categorical outcome. We evaluated effect modification by pre-pregnancy body mass index (BMI) categories.

Serum concentrations of PFHxS and PFOS were positively associated with GWG, GWG z-score and greater odds of excessive weight gain. In stratified models, positive associations with GWG were stronger among women with pre-pregnancy BMI classified as overweight compared to those with BMI in the obesity or normal/underweight categories. Mixture analyses suggested that positive associations were largely due to PFOS.

In a diverse population of pregnant women with PFAS serum concentrations typical of the U.S. general population, PFOS and PFHxS concentrations were associated with greater GWG. The influence of PFAS may differ by women's BMI status entering pregnancy.

Per- and polyfluoroalkyl substances

PFAS

Gestational weight gain

Institute of medicine recommendations

Pregnancy

© 2025 The Authors. Published by Elsevier GmbH.