Back pain before menstruation is mainly caused by the following reasons: 1. Before menstruation, the entire pelvic cavity is in a state of congestion, and if the uterus is in retroflexion and retroversion, it will stimulate the retroperitoneum and cause lumbosacral pain. 2. Due to chronic inflammation of the cervix, it will spread to the sacral ligament, and when inflammation occurs in the sacral ligament, before menstruation plus the pelvic cavity is in a state of congestion, it will also The situation of back pain will occur. Therefore, it is better to have a detailed gynecological examination after the menstruation. First of all, we should know the position of the uterus. If the uterus is in retroflexion and posterior tilt, the back pain may be relieved by resting on the bed before menstruation. In addition, you can find out whether there is inflammation in the sacral ligament, and if there is chronic cervicitis, active clinical treatment is given.