If back pain occurs a few days before menstruation, it is mainly caused by the following reasons. First, in the time before menstruation, the pelvis begins to be in a state of congestion, and if there is inflammation of the sacral ligament itself, the sacral ligament will also become congested due to inflammation. The congestion before menstruation will aggravate the congestion of the sacral ligament, so there will be lumbosacral pain, this situation in daily life will also show lumbosacral pain, and there will be an increase in vaginal discharge, often accompanied by chronic cervicitis clinical symptoms, it is recommended to actively anti-inflammatory treatment, can alleviate the occurrence of this situation. Secondly, due to the uterus in a retroflexed and tilted position, when the uterus is in a retroflexed and tilted position, the pelvis is in congestion, stimulating the posterior peritoneum can also cause lumbar pain, it is recommended to lie on the bed when resting, which will alleviate this situation. In addition, there is pelvic inflammation will also appear before menstruation back pain, it is recommended to clinically through the gynecological examination, to understand whether there is inflammation in the pelvic cavity, if necessary, can be given oral antibiotics to give treatment.