It is usually necessary to control the hyperthyroidism first, because hyperthyroidism itself can easily cause miscarriage, and high titers of maternal autoantibodies to the thyroid gland can stimulate the fetal thyroid gland to produce thyroid hormones through the placenta, thus affecting the development of the fetus; secondly, high doses of anti-thyroid medication can inhibit the development of the fetal thyroid gland. Therefore, it is best to consider pregnancy after hyperthyroidism is controlled and the medication is stopped. However, in clinical practice, we sometimes encounter patients with recurrent hyperthyroidism, and we sometimes recommend pregnancy when the patient is on maintenance doses of anti-thyroid medication. During pregnancy, thyroid work should be tested at least once a month, or even once every 3 weeks or so.