Hypothyroidism is usually not passed on to the baby when it is controlled by medication during pregnancy, but TGAb (antithyroglobulin antibodies) and TPOAb (antithyroid peroxidase antibodies) in the blood of pregnant women can pass through the placenta into the fetus and cause hypothyroidism. Hypothyroidism is a disease of reduced systemic metabolism due to decreased synthesis and secretion of thyroid hormones or diminished tissue action. Abnormal or absent thyroid function can affect the normal growth and development of the fetal nervous system, and screening for thyroid function should be performed during pregnancy. Untreated hypothyroidism in pregnant women may result in fetal miscarriage, death, fetal growth restriction, congenital defects, and delayed mental development. Clinical treatment of hypothyroidism aims to restore thyroid hormones to normal levels to prevent thyroid hormone deficiency from affecting fetal growth and development. Generally, hypothyroidism will not be passed on to the fetus after treatment. After controlling the condition of hypothyroidism, the growth and development of the fetus should be closely monitored. Meanwhile, TGAb and TPOAb in pregnant women may affect the fetus through the placenta during the treatment process, thus causing fetal hypothyroidism. After the newborn is born, the thyroid function should be checked in time. After the diagnosis of hypothyroidism is clear, treatment should be carried out under the guidance of doctors in time.