The impact of elevated thyroid stimulating hormone on female subfertility

Hypothyroidism is known to have a negative impact on female reproduction even in subclinical form, subclinical hypothyroidism (SH). This study aimed to investigate the association between elevated TSH level and reproductive outcome.

We retrospectively evaluated a total of 203 infertile women who first visited our infertility treatment division from January 1, 2009 to August 31, 2012, including 13 patients with TSH above 4.5 mIU/l (elevated-TSH patients), 11 of whom were diagnosed as SH, and 190 patients with normal TSH (normo-TSH patients). We evaluated them according to reproductive outcome, including clinical pregnancy, miscarriage, and live birth until April 31, 2014. We also aimed to redefine the upper limit of normal serum TSH level.

Multivariate analysis showed significant influence of elevated TSH on clinical pregnancy, although miscarriage and live birth were not affected. In addition, we revealed that the rate of decreased ovarian reserve and unexplained infertility was increased in patients with elevated TSH levels.

We found an association between elevated TSH and the decreased rate of clinical pregnancy. This might be related to an ovulatory disorder and pathophysiology of unexplained infertility. These results may reinforce the usefulness of TSH screening in infertility population.