Sonographic findings in maternal hyperthyroidism. Fetal hyperthyroidism/fetal goiter.

Maternal hyperthyroidism occurring during pregnancy is not rare. Its prevalence is quoted to be 0.2%. Graves' disease accounts for the majority of the cases of thy9 rotoxicosis in women of childbearing age with a tend· ency toward remission during pregnancy and exacerbation in the postpartum period. 1 Neonatal Graves' disease occurs in only 1 of 70 births of thyrotoxic mothers. 2 We report a case of maternal Graves' disease that was treated with propylthiouracil (PTU) through two consecutive pregnancies that resulted in two different forms of thyroid dysfunction in the two siblings. In the first pregnancy, a fetal goiter was documented, presumably secondary to PTU ingestion. In the following pregnancy, fetal tachycardia was the presenting symptom of fetal thyrotoxicosis, presumably secondary to placental passage of thyrotropin receptor antibodies (TRAb).3 To our knowledge, this is the first sonographic documentation of the latter.