The pain when you have your period is a sign of dysmenorrhea. There are primary dysmenorrhea and secondary dysmenorrhea. Most of the primary dysmenorrhea is caused by abnormal position or development of the uterus, excessive forward or backward bending of the uterus, and poor flow of menstrual blood during menstruation, which can also cause dysmenorrhea. In some cases, the endometrium has a high secretion of prostaglandins, which causes strong contractions of the uterus during menstruation, resulting in more severe menstrual pain. This kind of dysmenorrhea will be significantly reduced after the birth of a child, in case the pain is particularly severe, you can take oral painkillers, usually pay attention to keep warm and do not get cold. Secondary dysmenorrhea is mostly caused by endometriosis and adenomyosis, which must be treated for the original cause.