Abstract
This study aims to investigate associations between PM(10), PM(2.5), and NO(2) and maternal thyroid hormones. We investigated 443 pregnant women in Zhejiang, China with repeated examinations of serum thyroid hormones at 10, 17, and 32 weeks. Individual exposures to ambient air pollution were retrospectively calculated by inverse distance weighting interpolation. Multivariate linear mixed models were applied to estimate the association between air pollutants and thyroid hormones. PM(10) exposure was positively associated with TSH (β: 0.077 [95% CI: 0.003, 0.152]), and negatively associated with FT(3) (β: -0.041 [-0.057, -0.025]) and FT(4) (β: -0.036 [-0.055, -0.017]) during the 0-90 lag days (per IQR). Similarly, increased exposure to PM(2.5) was associated with decreased FT(3) (β: -0.016 [-0.032, -0.001]), and increased Tg (β: 0.147 [0.025, 0.269]). Evaluated NO(2) levels were associated with decreased FT(3) (β: -0.026 [-0.039, -0.014]) and FT(4) (β: -0.036 [-0.052, -0.020]), as well as increased Tg (β: 0.129 [0.011, 0.247]). The results indicate that exposure to ambient PM(10), PM(2.5), and NO(2) throughout the entire pregnancy adversely affects thyroid hormones, implying potential health implications of air pollution on maternal thyroid function.