Which medication should be used cautiously in pregnant women with hyperthyroidism?

In the context of treating hyperthyroidism in pregnant women, the use of radioactive iodine is approached with caution because it can have significant effects on the developing fetus. Radioactive iodine treatment can lead to hypothyroidism in the fetus or neonate and poses risks of thyroid gland damage due to the radioactive properties of the treatment.

In contrast, levothyroxine is commonly prescribed for managing hypothyroidism and is generally considered safe in pregnancy, while propranolol is often used to address symptoms of hyperthyroidism, such as tachycardia, without directly impacting thyroid hormone levels. Methimazole, while more effective than propylthiouracil, is associated with potential teratogenic effects, particularly in the first trimester; however, it is still used under careful monitoring.

Therefore, the recommendation to use radioactive iodine is given with caution in pregnant patients due to the potential harm it can cause to fetal thyroid function and overall development.