How to prevent hypothyroidism during pregnancy? I. Increase iodine intake in women during pregnancy. Because of the increased synthesis of thyroid hormones during pregnancy, increased renal iodine excretion, and increased fetal iodine requirements, pregnant women have significantly higher iodine requirements than non-pregnant women. Women who have adequate iodine intake before and during pregnancy are assured of sufficient iodine reserves in the thyroid gland to be able to meet the increased demand for thyroid hormones during pregnancy. The American Thyroid Association routinely recommends 150 micrograms of iodine supplementation per day in addition to the normal diet for all women during pregnancy and lactation. The best form of iodine supplementation is in the form of potassium iodide (or a multivitamin containing the same dose of potassium iodide), while food forms of iodine supplementation, such as seafood, do not meet this dose requirement. Second, perform thyroid function screening. From the beginning of pregnancy, fetal brain development is dependent on maternal thyroid hormones, and the first prenatal checkup for pregnant women is usually around 14 weeks, when the disadvantage of thyroid screening is that brain damage to the fetus may have already occurred. Timely screening and treatment of pregnant patients with hypothyroidism is important to save the brain development of the fetus. Therefore, hospitals and maternal and child health departments that are in a position to do so support screening for thyroid disease in women in early pregnancy. The screening indicators are TSH, FT4, and TPOAb. The timing of screening is chosen before 8 weeks of gestation. Preferably, screening is performed before pregnancy. Numerous medical research results and cost-benefit analyses have shown that screening the entire gestational population is preferable to no screening. With the progress of society and the development of medical care in China, it is expected that screening for thyroid disease in preconception, pregnancy and postpartum will be gradually implemented nationwide in the near future, which is of great significance to protect the health of women and children, improve the intellectual development of children and further improve the quality of the population.