(1) Surgery or iodine 131 treatment: 6 months before pregnancy; 48h before iodine 131 treatment, a pregnancy test is needed to appropriate whether or not to get pregnant; supplementation with eugenol to maintain TSH. (2) ATD therapy: methimazole and propylthiouracil have risks for both mother and fetus! Methimazole should be stopped and replaced by propylthiouracil when pregnancy is planned; Propylthiouracil is preferred during T1 (1~12 weeks) of pregnancy; After the period, switch to methimazole to avoid liver toxicity.