The thyroid gland is located in the neck below the front of the trachea, weighing about 20-40g, is the largest endocrine gland in the human body. The thyroid hormones secreted by the thyroid gland are involved in the metabolism of various substances in the body, and have a direct effect on tissue differentiation, growth and development, and reproductive physiology. The development and maturation of the gonads, and the maintenance of normal testicular spermatogenesis and menstruation also require the presence of normal thyroid function. The hypothalamic-pituitary-thyroid axis and the hypothalamic-pituitary-ovarian axis are connected and regulated by each other at various levels. are linked and regulated by each other. For example, thyroxine directly affects estrogen metabolism, and excess thyroxine accelerates the conversion of estrone to estriol. Elevated thyroxine promotes the secretion of luteinizing hormone (LH). Small amounts of thyroxine can stimulate the release of gonadotropins from the pituitary gland and ovarian secretion, while large amounts of thyroxine will cause ovarian dysfunction. There are two types of thyroid dysfunction: hyperthyroidism (hyperthyroidism) and hypothyroidism (hypothyroidism). With the development of hyperthyroidism, both axes are inhibited by feedback, the secretion and metabolism of ovarian hormones are blocked, and the process of decomposition, inactivation and elimination is accelerated. The endometrium gradually degenerates and atrophies, causing scanty menstruation and reduced menstrual flow until amenorrhea occurs. The amount of menstrual blood decreases until amenorrhea occurs. In mild cases of hyperthyroidism, ovulation may not be affected and pregnancy is possible. In severe cases, about 90% of the patients do not ovulate and cannot get pregnant naturally. Once pregnant, the rate of miscarriage is as high as 26%, and the rate of preterm labor is 15%. The incidence of hypertensive syndrome of pregnancy is 10 times higher than that of normal pregnancy, which may lead to thyroid crisis and threaten the patient’s life. Patients with severe or untreated hyperthyroidism should not get pregnant, and once pregnant, abortion should be performed. If a patient with hyperthyroidism becomes pregnant, she should be classified as a high-risk pregnancy, and should spend the pregnancy and delivery period under the joint supervision of obstetrics and endocrinology during the whole process of pregnancy. Regardless of hyperthyroidism or hypothyroidism, mild cases do not affect pregnancy, but the rate of miscarriage or stillbirth is higher, and severe cases of male patients may have loss of libido, impotence, reduced sperm count and infertility, while female patients with hypothyroidism tend to have excessive menstruation and frequent menstruation. If left untreated, it can also lead to infertility.