Abstract
This prospective birth cohort study evaluated the association of exposure to PM(2.5) (diameter ≤2.5 μm), PM(1-2.5) (1-2.5 μm), and PM(1) (≤1 μm) with maternal thyroid autoimmunity and function during early pregnancy. A total of 15,664 pregnant women were included at 6 to 13(+6) gestation weeks in China from 2018 to 2020. Single-pollutant models using generalized linear models (GLMs) showed that each 10 μg/m(3) increase in PM(2.5) and PM(1-2.5) was related with 6% (odds ratio [OR] = 1.06, 95% confidence interval [CI]: 1.01, 1.12) and 15% (OR = 1.15, 95% CI: 1.08, 1.22) increases in the risk of thyroid autoimmunity, respectively. The odds of thyroid autoimmunity significantly increased with each interquartile range increase in PM(2.5) and PM(1-2.5) exposure (P for trend <0.001). PM(1) exposure was not significantly associated with thyroid autoimmunity. GLM with natural cubic splines demonstrated that increases in PM(2.5) and PM(1-2.5) exposure were associated with lower maternal FT4 levels, while a negative association between PM(1) and FT4 levels was found when exposure exceeded 32.13 μg/m(3). Only PM(2.5) exposure was positively associated with thyrotropin (TSH) levels. Our findings suggest that high PM exposure is associated with maternal thyroid disruption during the early pregnancy.