Thyroid disorders; an insidious cause leading to female infertility

Abstract

The review aims to describe the effect of thyroid diseases on fertility. There are many causes of infertility in couples and thyroid dysfunction is a critical cause. Thyroid hormones and the hypothalamic-pituitaryovarian axis interact in several ways and thyroid hormones may modulate ovarian functions. Hypothyroidism causes ovulatory dysfunction and luteal hypoplasia due to decreased progesterone production. Levothyroxine supplementation restores the ovulatory function and ultimately resolves the fertility issues. Regarding the elevated concentrations of antithyroid antibodies in infertile women, high concentrations are associated with a three- to four-fold increased risk of recurrent miscarriages. Moreover, women with positive antithyroid antibodies tend to develop thyroiditis postpartum. In assisted reproduction cycles the presence of antithyroid antibodies is correlated with poorer embryo quality, lower fertilization rates and increased risk of spontaneous abortion. Lastly, hyperthyroid women, especially with thyrotoxicosis, have menstrual disorders such as oligomenorrhea and polymenorrhea. In hyperthyroid women the incidence of infertility is higher.