The back pain before menstruation may be caused by PMS, pelvic inflammatory disease, endometriosis and other reasons. 1. Premenstrual syndrome: the cause of premenstrual syndrome is not yet clear, and it is considered to be caused by neurotransmitter abnormalities, ovarian hormone imbalance and other factors. Patients will have breast swelling and pain, back pain, irritability and other manifestations, so patients will have not yet menstruation back pain performance. 2. Pelvic inflammatory disease: Pelvic inflammatory disease is caused by various types of pathogen infection. Patients will show lumbosacral pain, increased leukorrhea, and lumbar pain will worsen before and after menstruation, so there will be no menstrual back pain. 3. Endometriosis: Patients with endometriosis may exhibit progressively worsening dysmenorrhea, which can start from premenstrual period with abdominal pain and low back pain. The patient has not yet menstrual back pain performance, should promptly consult a doctor, the doctor will take appropriate measures for the cause of treatment.