Impact of thyroid autoantibodies and serum TSH level on clinical IVF outcomes

Objective: This study aimed to investigate the impact of thyroid autoantibodies and serum TSH levels on clinical IVF outcomes. Materials and methods: This study included 260 Korean women scheduled for their first IVF between 2013 and 2017. Serum levels of thyroid hormone, TSH, and antibody for thyroid peroxidase and thyroglobulin were measured just before the first ovarian stimulation. Clinical pregnancy rate (PR), ongoing PR, and miscarriage rate were analyzed according to thyroid autoimmunity and serum TSH levels. The primary outcome was ongoing PR beyond 12 weeks of gestation. Results: The ongoing PR and miscarriage rates were similar between women with positive (n = 29) and negative autoantibodies (n = 186). In women with subclinical hypothyroidism (serum TSH ≥4.2 μIU/mL), ongoing PR was significantly lower than euthyroid women (22.2%, vs. 44.7%, p = 0.045), but miscarriage rate was similar. The group with serum TSH ≥3.4 μIU/mL showed a significantly lower ongoing PR (23.9% vs. 46.7%, p = 0.005) and significantly higher miscarriage rate (38.9% vs. 14.1%, p = 0.020). In multivariate logistic regression analysis, serum TSH ≥3.4 μIU/mL was an independent unfavorable predictor for ongoing PR (odds ratio 0.375, p = 0.013). Conclusion: Thyroid autoantibodies did not affect clinical IVF outcomes, but women with serum TSH ≥3.4 μIU/mL demonstrated poor IVF outcomes.