A 45-year-old woman whose period came back after 3 months of stopping is considered to be suffering from perimenopausal syndrome, cervical polyps, cervical cancer, and other diseases such as ovarian cancer. 1. Perimenopausal syndrome: Perimenopausal syndrome is considered to be caused by heredity and hormonal changes in the body. Patients will have sudden stop of menstruation, shortening of menstrual cycle, heavy menstrual flow, hot flashes, excessive sweating, emotional excitement and other manifestations. Therefore, if a 45-year-old woman has perimenopausal syndrome, she will have her menstruation come back after 3 months. 2. Cervical polyps: the cause of cervical polyps is still unclear, and it is considered to be caused by cervical infection and abnormal hormone levels in the body. The patients can be manifested as postmenopausal bleeding, bleeding after sexual intercourse, etc. Therefore, the 45-year-old patients will have the symptom of menstruation coming back after 3 months of stopping. 3. Cervical cancer: cervical cancer is mainly related to human papilloma virus infection, and patients will have symptoms such as contact bleeding, postmenopausal vaginal bleeding, prolonged menstrual period and abnormal vaginal discharge. If 45-year-old women develop cervical cancer, they will have the symptom of menstruation coming back after 3 months of menopause. 4. Other: 45-year-old women who have menstruation again after 3 months of menopause are also considered to be caused by ovarian cancer, endometrial cancer and other diseases. It is recommended that 45-year-old women who have menstruation again after 3 months of stopping menstruation should consult a doctor in time, who will take targeted measures to treat the disease according to the cause of the disease.