1. What are the diagnostic criteria for clinical hypothyroidism in pregnancy? The diagnostic criteria for clinical hypothyroidism in pregnancy are: TSH > upper limit of gestational reference value and FT4 < lower limit of gestational reference value. The reference range of pregnancy-specific serum thyroid indicators (referred to as gestational reference values) is divided into two categories, one is the gestational reference values established by the hospital or region, and the other is the reference values recommended by the guidelines. T1 (0-13+6 weeks of gestation), i.e. 0.1-2.5 mIU/L in early pregnancy; T2 (14-27+6 weeks of gestation), i.e. 0.2-3.0 mIU/L in mid-pregnancy; T3 (28-41+6 weeks of gestation), i.e. 0.3-3.0 mIU/L in late pregnancy. The 2011 version of ATA guidelines also suggests that women with TSH >10 mIU/L in T1 pregnancy The diagnosis of clinical hypothyroidism can be made with or without FT4 reduction. However, there is no academic consensus on the criterion of TSH>10mIU/L. 2.What are the risks of clinical hypothyroidism during pregnancy on pregnancy outcome? Clinical hypothyroidism during pregnancy impairs the neurointellectual development of the offspring and increases the risk of preterm birth, miscarriage, low birth weight, stillbirth and gestational hypertension, and the evidence is certain that treatment must be given. What are the goals of treatment for clinical hypothyroidism in pregnancy? The ATA suggests that the TSH targets for levothyroxine (L-T4, eugenol, retinoids, etc.) in the treatment of clinical hypothyroidism in pregnancy are: 0.1-2.5 mIU/L in T1, 0.2-3.0 mIU/L in T2, and 0.3-3.0 mIU/L in T3. Once clinical hypothyroidism is identified, treatment should be started immediately to achieve the above treatment targets as early as possible. 4.Treatment drugs and dose for clinical hypothyroidism in pregnancy? L-T4 therapy is preferred for clinical hypothyroidism in pregnancy. The starting dose of L-T4 is 50~100μg/day, and the dose should be increased according to the patient’s tolerance level to reach the target as soon as possible. Slowly increasing doses are required for those with co-morbid heart disease. For patients with severe clinical hypothyroidism, give twice the replacement dose within a few days of starting treatment so that the extra-thyroidal T4 pool returns to normal as soon as possible. 5. Under what conditions can a woman with clinical hypothyroidism become pregnant? Women with established clinical hypothyroidism who plan to become pregnant need to control serum TSH at 0.1~2.5 mIU/L level before becoming pregnant. 6.How often should clinical hypothyroidism be monitored during pregnancy? The frequency of monitoring thyroid function during the first half of pregnancy (1~20 weeks) is once every 4 weeks. Serum thyroid function indicators should be tested once in 26~32 weeks of pregnancy. 7.How to adjust the postpartum L-T4 dose in clinical hypothyroidism during pregnancy? The L-T4 dose should be reduced to the pre-pregnancy level after delivery in pregnant women with clinical hypothyroidism, and the serum TSH level should be rechecked 6 weeks after delivery to adjust the L-T4 dose.