Abstract
There has been little convincing evidence for the teratogenesis of antithyroid drugs. And there is little evidence for a causal relationship between maternal hyperthyroxinemia and malformations.In mothers with active Graves’ hyperthyroidism, maintaining free T4 levels within the normal range seems unlikely to cause mental retardation in their infants since hypothyroidism due to this treatment is mild enough and its duration is too short to affect intellectual development. Controlling maternal hyperthyroidism is important to avoid complications in pregnancy which indirectly affect infants. It may therefore be acceptable to maintain maternal free T4 levels within the normal range when hyperthyroidism has not been well controlled or there are complications, but close monitoring of the infant’s thyroid status is essential. When fetal hyperthyroidism is suspected in mothers who have reached remission status after surgery or radioiodine therapy for Graves’ disease, giving iodine to the mother may be beneficial for the fetus.
