Thyroid Autoimmunity and Infertility
Autoimmune thyroid disease (AITD) is one of the most common endocrinopathies and is more prevalent in women. The circulating thyroid antibodies and the hypothyroidism that often follows AITD have effects on many tissues. The endometrium and ovaries are not spared, and therefore this common morbidity might have an impact on fertility. Despite challenging data interpretation and contradictory results, a general takeaway from published studies is that there is a higher incidence of elevated levels of thyroid-stimulating hormone (TSH) and the presence of thyroid antibodies among infertile women. While a single specific and direct pathophysiological mechanism through which autoimmune thyroid disease causes infertility has not been identified, there are multiple gynecological comorbidites that might perpetuate infertility (endometriosis, premature ovarian failure, polycystic ovaries) and defective immunological functions (a shift to a proinflammatory Th1 response, increased levels of natural killer cells, cross-reactivity of antigens etc.) that are affecting fertility. There is insufficient evidence that suggests levothyroxine (LT4) treatment can help women suffering from AITD conceive and carry out a pregnancy.