Menstruation generally refers to menstruation. Menstrual stomach pain may be related to increased prostaglandin levels, pelvic inflammatory disease, endometriosis, and so on. 1. Increased levels of prostaglandins: When you have your period, a significant increase in the level of prostaglandins in a woman’s body may induce uterine contractions, causing menstrual stomach pain, the pain is not very obvious, is a normal physiological manifestation of the pain, and does not need to be treated. 2. Pelvic inflammatory disease: bacteria and other pathogens invade the pelvic tissues may cause local congestion and edema, and when you have your period, it may lead to aggravation of the condition, which may cause stomach pain. 3. Endometriosis: When menstruation comes, the active endometrium grows in the myometrium or outside the uterus, which may lead to stomach pain.