Graves Hyperthyroidism and Pregnancy: A Clinical Update

Komal Patil-Sisodia, MD; Jorge H. Mestman, MD


Endocr Pract. 2010;16(1):118-129. 

In This Article


Studies have shown that breastfeeding is safe for infants when mothers are taking antithyroid drugs. In one such study, breastfed infants with elevated TSH levels at birth had normalization of their TSH levels despite administration of PTU to the mothers.[57] Another study showed no evidence of infant hypothyroidism when hyperthyroid mothers were treated with methimazole, 20 to 30 mg daily, in the postpartum period during breastfeeding. Furthermore, the physical and intellectual development of children, aged 48 to 86 months, remained unchanged in comparison with development of control children when assessed by the Wechsler and Goodenough tests.[58] The conclusion drawn from these studies is that breastfeeding is safe in mothers taking moderate dosages of antithyroid drugs (PTU, less than 150–200 mg daily, or methimazole, less than 10–20 mg daily). If a mother is taking an antithyroid drug, it is currently recommended to screen infants with thyroid function tests and to administer the medication to the mother in divided doses after each feeding.