Management of hyperthyroidism in pregnant women 1. If TSH concentrations are measured below normal during pregnancy, normal physiologic changes during pregnancy and due to severe pregnancy vomiting must be excluded before considering hyperthyroidism, as hyperthyroidism can have serious effects on both mother and fetus. The basis of autoimmune disorders, goiter, and the presence of TRAb can help identify whether it is Graves’ disease or a toxic state of the thyroid gland during pregnancy. 2, For obvious hyperthyroidism or hyperfunctioning adenoma due to Graves’ disease, antithyroid medication must be administered. Patients who are first diagnosed must start treatment immediately, and those who have been diagnosed and started treatment before pregnancy must have their medication dose adjusted to ensure that free thyroxine (FT4) levels are at the upper limit of normal for non-pregnancy. 3. There is evidence that methimazole may be associated with congenital malformations in the fetus, and therefore propylthiouracil should be used as a first-line agent, especially in early pregnancy – the period of organogenesis. Methimazole should be considered only if the patient cannot tolerate propylthiouracil or if the side effects are too great. Subtotal thyroidectomy may be used as a treatment for maternal Graves’ disease if: (1) there are severe side effects of antithyroid medication; (2) high doses of antithyroid medication must be continued to maintain thyroid function; (3) the patient is not adherent to antithyroid medication and the hyperthyroidism is not effectively controlled; (5) there is no evidence that treatment of subclinical hyperthyroidism improves obstetric There is no evidence that treatment of subclinical hyperthyroidism can improve obstetric outcomes, and treatment may have potential side effects on the fetus. 6. TRAb can stimulate the fetal thyroid gland through the placenta, so TRAb needs to be measured before and during pregnancy in mothers with: 1) current Graves’ disease; 2) a history of Graves’ disease; 3) a history of iodine-131 therapy or thyroid surgery; 4) a history of Graves’ disease neonatal output. Patients who are TRAb negative and who do not require antithyroid medication have a low chance of having abnormal thyroid function in their fetuses and newborns. 7. Iodine-131 therapy must be avoided in women who are or may become pregnant, and if inadvertently iodine-131 therapy has been administered, the pregnant woman must be informed of the risks of radiation to the fetus, including the fact that iodine-131 therapy can cause thyroid gland destruction in the fetus if administered after 12 weeks of gestation. There is no evidence to support or oppose termination of pregnancy after iodine-131 treatment. 8. In pregnant women with elevated TRAb or on antithyroid medication, ultrasound of the fetus must be performed for abnormalities in fetal thyroid function such as growth retardation, edema, goiter, or heart failure. 9. Cord blood should be collected for testing only if the available clinical evidence is insufficient to determine fetal thyroid disease and if the information provided by cord blood assay is likely to change the treatment plan. 10. All newborns whose mothers have Graves’ disease must have their thyroid function measured for the presence of abnormal thyroid function and for necessary treatment.