The Use of Antithyroid Drugs in Pregnancy and Lactation

The management of hyperthyroidism in the pregnant woman has been the topic of several recent reviews (1–6) and case series (7–8). These papers have discussed maternal-fetal thyroid relationships, the epidemiology of maternal hyperthyroidism, causes of gestational thyrotoxicosis, the clinical and laboratory diagnosis of hyperthyroidism in pregnancy, therapy with ATDs, surgery, b adrenergic blocking drugs, and iodides, as well as the consequences of inadvertent radioiodine therapy and the implications of breast feeding. The purpose of this discussion is to provide an in depth examination of the use of ATDs in the pregnant hyperthyroid woman, rather than to present comprehensive guidelines for the treatment of hyperthyroidism during pregnancy furnished in other reviews (1–6). The subject continues to engender controversy because of the lack of prospective clinical trials and the relative rarity of the condition, occurring in only 1 of 1000–2000 pregnancies (7, 8). With more women receiving radioiodine before conception, the frequency may be even lower in the future.