Perfluoroalkyl substances, glucose homeostasis, and gestational diabetes mellitus in Chinese pregnant women: A repeat measurement-based prospective study.

•PFASs, covariates, FBG, FIns, and HOMA-IR were repeatedly measured during pregnancy.•Physical activity and intakes of meat, vegetable, and aquatic products were used as covariates.•Serum PFOA was positively associated with FIns, HOMA-IR, and OGTT blood glucose.•Serum PFOS tended to be negatively associated with FBG and OGTT blood glucose.•Different association trends with GDM were seen between serum PFOA and PFOS.