Effect of moderately increased thyroid-stimulating hormone levels and presence of thyroid antibodies on pregnancy among infertile women.

PurposeTo study the effects of mildly elevated thyroid-stimulating hormone (TSH) levels and thyroid antibodies on pregnancy rates among infertile women and their potential contribution to prolonged infertility treatment.MethodsThis case-control study included 1479 women who underwent infertility treatment between March 2015 and August 2017. Cumulative pregnancy and miscarriage rates after assisted reproductive technology (ART) or non-ART treatments were compared between women with TSH <2.5 mIU/L and those with TSH 2.5-3.5 mIU/L and between women with and without thyroid antibody positivity.ResultsThe cumulative pregnancy rate of women with TSH 2.5-3.5 mIU/L was similar to that of women with TSH <2.5 mIU/L in the non-ART (hazard ratio [HR], 0.85; 95% confidence interval [CI], 0.56-1.23) and ART (HR, 1.17; 95% CI, 0.93-1.47) groups. Thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) had no correlation with cumulative pregnancy rates. In the non-ART and ART groups, HRs for TgAb were 0.87 (95% CI, 0.55-1.32) and 1.09 (95% CI, 0.84-1.39) and HRs for TPOAb were 0.88 (95% CI, 0.52-1.39) and 1.29 (95% CI, 0.97-1.68), respectively.ConclusionsCumulative pregnancy rates and miscarriage rates were similar between women with TSH <2.5 mIU/L and those with TSH 2.5-3.5 mIU/L and were independent of thyroid antibody positivity.