The causes of low back pain in women during menstruation are as follows: a. Due to excessive pelvic congestion and accelerated blood circulation during menstruation, pain may occur due to pressure on the nerves in the lower back. 2. When women have menstruation, due to the decrease of hormone level, they often have physical fatigue and weakness, and some women may show mainly lumbar pain. When women’s uterus is posterior, due to the poor flow of menstrual blood, they may also have low back pain, which is related to the position of the uterus. Therefore, if you have low back pain when you have menstruation, you should pay attention to proper rest, and you can give appropriate massage or hot compress to your lower back to get relief. If the lumbar pain is more severe, if necessary, you need to go to the hospital for examination and treatment to observe whether there is lumbar spine pathology, so as not to delay the diagnosis and treatment of the disease.