Associations of combined PFAS exposure with maternal thyroid hormone levels based on weighted quantile sum (WQS) regression analysis (n=726), adjusting for maternal age, race/ethnicity, smoking habits, parity, gestational week at blood draw, and fish intake. We calculated two separate WQS indices for associations with each hormone, one in the positive direction of effect and one in the negative direction of effect. Results of each analysis include the WQS beta and 95% confidence interval for the effect of combined exposure to the PFAS mixture on (a) total T4 (μg/dL), (b) ln-FT4I, and (c) ln-TSH levels (mIU/mL), with corresponding weights for the contributions of individual PFAS to the overall effect.