A Review of Autoimmune Thyroid Diseases and Their Complex Interplay with Female Fertility

Abstract Hashimoto thyroiditis and Graves' disease are autoimmune thyroid disorders that are common in women of reproductive age and have a complex relationship with female fertility and health of the maternal–fetal dyad. Both hyperthyroidism and hypothyroidism, whether subclinical or overt in severity, directly or indirectly affect nearly every level of the hypothalamic–pituitary–ovary axis, uterine and ovarian function, as well as fetal development from implantation through delivery. Autoimmunity itself also appears to negatively impact both spontaneous and assisted fertility, as well as miscarriage risk, although the mechanism remains unclear, and the presence and magnitude of risk is variable in published literature. While treatment of overt hyperthyroidism and hypothyroidism is unequivocally recommended by professional societies, the impact of treatment on fertility outcomes, and the role of treatment in subclinical thyroid disease is more controversial. Unfortunately, levothyroxine has not been shown to abrogate the risk of subfertility and miscarriage observed in euthyroid thyroid autoantibody positive women.