Hypothyroidism (hypothyroidism) is a systemic hypometabolic syndrome caused by various causes of hypothyroidism or thyroid hormone resistance. The onset of hypothyroidism in adults is called “adult hypothyroidism”. If the disease develops during embryonic or infantile life, it can seriously affect brain and body growth and development, resulting in dementia and dwarfism. Hypothyroidism can lead to infertility, spontaneous abortion, fetal arrest, premature birth, stillbirth, placental abruption, hypertension, preeclampsia, cardiac dysfunction, fetal growth restriction, low birth weight, fetal malformation, stillbirth, and high perinatal morbidity and mortality. Studies have shown that the 4th-6th months of gestation is the period of rapid fetal brain development, and inadequate maternal thyroid hormone supply can lead to fetal neurodevelopmental disorders, and this damage is irreversible. Adequate thyroxine treatment restores normal thyroid function and greatly reduces the incidence of maternal and fetal complications. Therefore, an adequate supply of thyroid hormones during pregnancy is essential to ensure the health of the mother and her offspring.