A patient had been married for several years without pregnancy and had sporadic menstruation. For several years, she was treated as polycystic ovary syndrome and took Da Ying 35 to maintain her menstruation. She was referred to a TCM doctor by a friend once and stopped taking Western medicine while taking Chinese medicine. The diagnosis of “hypothyroidism” was established. The diagnosis of “hypothyroidism” was confirmed. As you can imagine, the lack of thyroid hormone was the main cause of her poor menstruation and miscarriage. To this day, she is baffled that after years of treatment for menstrual problems, none of the doctors have considered the thyroid gland to be the problem! So when you suffer from reduced menstruation or amenorrhea, spontaneous miscarriage, infertility and other gynecological problems, have you ever thought that the thyroid gland is to blame? There are indeed many gynecological diseases closely related to thyroid dysfunction in clinical cases, such as Chen, 27 years old, a teacher, who had a miscarriage after 2 months of pregnancy, as a result of hypothyroidism; Shi, 21 years old, a student, who had amenorrhea for several months, due to hyperthyroidism; in short, abnormal thyroid function can cause menstrual cycle disorders, become longer, shorter or even lead to premature ovarian failure. We must not ignore the small thyroid gland located in front of the neck and below the throat knot, which has an important significance for the human body. The hormone secreted by the thyroid gland is an important hormone for the growth, development and maturation of the human body, and has an important role in regulating the various sex hormones that maintain a woman’s menstruation. A lot of information shows that thyroid hormone deficiency can cause delayed gonadal development, non-ovulation, infertility, menstrual disorders, spontaneous abortion, functional uterine bleeding, etc.; too much thyroid hormone can cause scanty menstruation, prolonged menstruation, less likely to conceive, miscarriage, premature birth, fetal malformation, etc. Gynecological diseases caused by thyroid hormone deficiency include: 1) excessive thyrotropin (TSH) which causes hyperprolactinemia (PRL), thereby suppressing ovarian function and amenorrhea; 2) anovulatory functional bleeding; 3) pre-eclampsia and inevitable miscarriage; 4) scanty menstruation and even premature ovarian failure. The main gynecological diseases caused by hyperthyroidism are menstrual disorders, amenorrhea and infertility. Therefore, we should pay attention to the condition of menstruation when we have problems with the thyroid gland, and prevent and control it early; conversely, we need to exclude the thyroid gland when we have problems with menstruation. The number of gynecological diseases caused by thyroiditis and thyroid nodules is increasing, so we should not take it lightly and ignore the function of the thyroid gland.