The Impact of Preconceptional Serum TSH Levels between 2.5 and 4.0 mIU/L on Infertile Women Going through Their First IUI Treatment Cycle

OBJECTIVE: To evaluate the impact of preconceptional serum TSH levels on the clinical outcomes of infertile patients undergoing their first IUI treatment cycle. METHOD: This was a retrospective study. Euthyroid patients undergoing the first cycle of IUI treatment from Jan 2017 to Aug 2018 were included. The patients were divided into a normal high TSH level (2.5–4.0 mIU/L) group and a low TSH level (0.4–2.5 mIU/L) group. Then, different factors were included separately to compare the outcomes between normal high and low TSH levels. The primary outcomes were clinical pregnancy rates, implantation rates, and miscarriage rates. The secondary outcomes were obstetric outcomes such as single live birth rates, birth length, birth weight, and duration of gestation. RESULTS: Initially, 1856 patients were included, and 371 patients were excluded for different reasons. A total of 1485 patients were finally included in the analysis. The general parameters between normal high and low TSH levels were similar except for infertile duration and female BMI, which were, however, significantly different between AID-IUI patients and AIH-IUI patients (P=0.005 and P=0016). No significant differences were found in terms of either primary outcomes or secondary outcomes. CONCLUSION: Normal high-serum TSH levels within the reference range (0.4–4.0 mIU/L) measured before treatment seemed to have no adverse impact on the clinical outcomes of patients undergoing their first IUI treatment cycle.