Management of Thyroid Disorders Before Assisted and Spontaneous Pregnancies

Severe thyroid dysfunction may lead to menstrual disorders and infertility. Fertility problems may persist even after restoring normal thyroid function, and then an assisted reproductive technology (ART) may be considered as a therapeutic option. Prior to an ART treatment, an ovarian hyperstimulation is performed, leading to high oestradiol levels, which may lead to hypothyroidism in women with thyroid autoimmunity (TAI), necessitating thyroid hormone supplements (LT4) before pregnancy. Moreover, women with the polycystic ovarian syndrome and idiopathic infertility have a higher prevalence of TAI. Women with a known hypothyroidism before pregnancy and treated with LT4 should have a serum TSH <2.5 mIU/L, both in case of assisted and spontaneous pregnancies. Women with Graves’ disease desiring pregnancy should be advised of the increased risk of maternal and fetal complications and about the possible side effects of antithyroid drugs. If necessary, pregnancy must be postponed until euthyroidism is reached and confirmed. With the exception of women planning ART or those known to have TAI, at present there are no recommendations regarding universal screening for thyroid function in the preconception phase.