Gestational diabetes mellitus in relation to serum per- and polyfluoroalkyl substances: A scoping review to evaluate the need for a new systematic review

Background Per- and polyfluoroalkyl substances (PFAS) were used or are being used in the manufacturing of products, including consumer-use products. The resulting environmental contamination has led to widespread human exposure. This review aimed to scope the characteristics of evidence covered and applied methodology of evidence to understand -- regardless of any results on the association of gestational diabetes mellitus (GDM) and PFAS -- if a new systematic review would be justified. Methods We systematically identified reports investigating associations of PFAS with GDM following a pre-specified and pre-registered PECO framework and protocol. Results The previous systematic reviews included 8-11 reports and either conducted meta-analyses stratified by comparator, analyzed results based on only high and low exposure categories, or pooled results across comparators. Included 20 reports presented data on 24 PFAS with PFOA, PFOS, PFHxS, PFNA, and PFDA being examined in almost all. The comparators employed were heterogeneous across the reports. Conclusions Because data from at least one new report on GDM is available since the previous systematic reviews and heterogeneous comparators, an updated systematic review using SWiM could add value to the literature.