Drug Therapy for Graves' Disease during Pregnancy

To the Editor: I greatly enjoyed reading the article by Momotani et al. (July 3 issue)* regarding antithyroid therapy for Graves' disease during pregnancy. There is, however, one comment that needs to be made. In their study, Momotani et al. found no difference between the group of women with hyperthyroidism treated with propylthiouracil and the group of women with hyperthyroidism treated with methimazole, in the proportion of fetuses with suppressed thyroid function. This was contrary to the investigators' expectations, since, “because of its reported limited placental transfer, propylthiouracil is widely preferred over methimazole.” One might be tempted to conclude that.