The reason for the soreness of the lower back after the menstrual period is that the patient should take rest and get enough sleep, and can also apply hot compresses to the lower back to help relieve the pain. 2. 3. Patients wearing intrauterine devices may also experience lumbar pain after menstruation, which is due to the stimulation of foreign bodies in the uterus and the contraction of the uterus after menstruation, when the endometrium is thin. It is recommended that women should keep their vulva clean during menstruation, avoid getting cold and tired, ensure sufficient sleep, and prohibit sexual intercourse and tub bathing.