Low back pain before menstruation is a common symptom of dysmenorrhea. The main causes are as follows: primary dysmenorrhea if no abnormal lesions in the pelvic organs are found after detailed clinical examination. If no abnormal lesions in the pelvic organs are found after detailed clinical examination, it is called primary dysmenorrhea. If abnormal lesions in the reproductive organs are found after examination, such as endometriosis, pelvic inflammatory disease, pelvic tumor, etc., it is called secondary dysmenorrhea. Abnormal position of the uterus, such as anterior tilt, posterior flexion, prolapse and so on. In pelvic tumor, low back pain occurs due to compression of nerves by uterine fibroids, cervical cancer, ovarian cysts, etc. or infiltration of pelvic connective tissue by cancer cells. Having too many children and too many abortions can also cause low back pain. Patients suffering from pelvic inflammatory disease experience low back pain due to inflammatory stimulation.