Prenatal management of fetal goiter alternating between hypothyroidism and hyperthyroidism in a mother with Graves' disease.

We present a rare documented case with consecutive hypo- and hyperthyroidism during fetal life. First, hypothyroidism was due to transplacental passage of antithyroid drugs. After the mother's thyroidectomy, fetal hyperthyroidism was due to transplacental passage of persistent anti-thyrotropin receptor antibodies. Fetal goiter disappeared after adjusting maternal treatment.