The associations between concentrations of gestational bisphenol analogues and thyroid related hormones in cord blood: A prospective cohort study

Animal studies indicated that Bisphenol analogues (BPs) exhibited potential thyroid toxicity. However, little is known of the associations between maternal BPs exposure and offspring's thyroid related hormones in humans. On the basis of Shanghai-Minhang Birth Cohort study, we analyzed BPs in maternal urine collected at the third trimester of pregnancy. Thyroid related hormones (THs), including total triiodothyronine (TT3), free triiodo-thyronine (FT3), total thyroxine (TT4), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were measured in cord blood samples. We performed multiple linear regression and Bayesian kernel machine regression (BKMR) models to explore the single and joint effects of gestational BPs exposure on thyroid related hormones in cord blood among 258 mother-child pairs. Statistically significant inverse associations of catego-rized BPA with FT3 and TT4 concentrations were observed. We also found a significant association between the mixture of BPs in maternal urine and increased concentration of TT3 in cord blood and a marginally significant association between BPs mixture and increased FT3 concentrations. Further associations of BPA with lower TT4/ FT4 and of Bisphenol AF (BPAF) with higher TT3/FT3 were also suggestive, by BKMR model, when other BPs were fixed at 25th percentiles. It was concluded that prenatal BPs exposure was associated with THs in cord blood. Exposure to BPA and BPAF might have large contributions to the effects on thyroid function than other bisphenols.