Objective To assess the status of bisphenol A (BPA) exposure among pregnant women during different trimesters of pregnancy in Shanghai and the relationship between urinary BPA and indices of thyroid function.
Methods The study participants included 210 (70 for each trimester) pregnant women from seven districts of Shanghai, China. Maternal urinary total BPA was detected by solid phase extraction-high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Serum indices of thyroid function including free triiodothyronine (FT3), free thyroxine (FT4), thyroid stimulating hormone (TSH), thyroglobulin antibody (TGAb) and thyroid peroxidase antibody (TPOAb) were detected. Associations between urinary BPA and serum indices of thyroid function were estimated by Pearson correlation analysis and multiple linear regression analysis.
Results The positive rate of urinary BPA of studied pregnant women was 95.7%. The mass concentrations of urinary BPA ranged from undetected to 11.99 μg/L, and showed a skewed distribution. The median (P25, P75) of urinary BPA mass concentration after adjusting for urine specific gravity was 0.53 (0.36, 0.83) μg/L. There was no significant difference of urinary BPA mass concentrations among the pregnant women grouped by different trimesters of pregnancy. The results of Pearson correlation analysis showed that adjusted urinary BPA mass concentration was positively related to serum TGAb level in the first and third trimesters, respectively (r=0.396, P=0.002; r=0.440, P=0.000). After adjusting for age, body mass index in pregnancy, and gestational weeks, the results of multiple linear regression analysis suggested that they were still positively related (b=0.369, 95%CI:0.206-0.532, P=0.000). There was no significant association between urinary BPA and other selected thyroid function indices.
Conclusion Shanghai pregnant women are exposed to BPA generally. BPA exposure during pregnancy may affect the level of serum TGAb.
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