Impact of endocrine disrupting chemical exposure on thyroid disruption and oxidative stress in early pregnancy

Non-persistent endocrine disrupting chemicals (EDCs) are associated with increased oxidative stress and disrupted thyroid-stimulating hormone (TSH) during pregnancy; however, the results of previous studies are inconsistent. This study assessed the concentrations of 15 non-persistent chemicals, TSH, and oxidative stress biomarkers in pregnant women during the first trimester in Korea. This study was a prospective cohort study, recruiting a total of 242 pregnant women from March 18, 2022 to March 17, 2023. Pregnant women who agreed to participate in the study provided blood and urine samples in the first and third trimesters of pregnancy. Concentrations of three bisphenols, four parabens, triclosan, benzophenone-3, two volatile organic compounds (VOCs), and four polycyclic aromatic hydrocarbons (PAHs) were analyzed in urine samples. TSH, malondialdehyde (MDA), and 8-hydroxydeoxyguanosine (8-OHdG) were measured as biomarkers of thyroid function and oxidative stress. The geometric mean concentration of the chemicals ranged from 0.07 to 45.20 μg/g creatinine, and were lower or similar to those in previous studies, except for ethyl paraben (EP). Spearman's coefficients of correlation ranged from -0.26 to 0.51. A multiple linear regression model was constructed after adjusting for covariates (maternal age, pre-pregnancy body mass index, education level, income, residence area, parity, and maternal cotinine level). BPF (ß = -0.184, p = .020, 95 % CI = -0.223 to -0.020), 1-hydroxypyrene (1-OHP) (ß = -0.197, p = .046, 95 % CI = -0.915 to -0.009), and , 2-hydroxyfluorene (2-FLU) (ß = 0.199, p = .026, 95 % CI = 0.053 to 0.819) were significantly associated with TSH. trans, trans-muconic acid (t,t-MA) (ß = 0262, p = .001, 95 % CI = 0.050 to 0.181) showed a positive association with malondialdehyde (MDA) as a biomarker for oxidative stress. Therefore, pregnant women should minimize their exposure to EDCs, which impact oxidative stress and TSH in the early stages of pregnancy.