The impact of thyroid function on intrauterine insemination outcome - a retrospective analysis

Background: Hashimoto's thyroiditis is the most common endocrinopathy in premenopausal women, and is associated with various gynecological problems, including recurrent miscarriage and unexplained infertility. A possible influence of Hashimoto's thyroiditis on the success of intrauterine insemination seems likely, but has not been evaluated as yet. Therefore, the aim of our study was to retrospectively analyze the impact on intrauterine insemination outcome of thyroid function and markers suggestive for Hashimoto's thyroiditis. Methods: Retrospective cohort study in a tertiary care center of 540 women who underwent Intrauterine Insemination. The clinical pregnancy rate was the main outcome parameters. The following possible influencing factors were tested: thyroid-stimulating hormone (TSH); thyroid autoantibodies; age; body mass index; type of sterility (primary/secondary); parity; male factor; presence of PCO syndrome; ovulation induction; ovarian stimulation; and current thyroid medication. Results: The overall clinical pregnancy rate was 6.9% (37/540). Age, thyroid hormone supplementation for thyroidstimulating hormone (TSH) levels > 2.5 micro-IU/ml, and ovulation induction with HCG were significantly predictive in the multivariate analysis (p < 0.05) as influencing factors for the pregnancy rate after intrauterine insemination. Conclusions: Women undergoing intrauterine insemination seem to benefit from a strict thyroid hormone supplementation regimen in order to achieve lower TSH levels.