It is quite common for women to have stomach pain when they have their period. The main reasons for stomach pain during menstruation are the following: First, the secretion of prostaglandins in women’s bodies will increase after menstruation, and the secretion of prostaglandins will easily lead to spasm of the uterine muscles, which will cause stomach pain. Secondly, during menstruation, the pelvic cavity of women is in a state of congestion, and pelvic congestion can lead to small stomach cramps, back pain, and occasionally anal cramps. Third, during menstruation if rest is not good, overexertion will lead to pelvic congestion symptoms aggravated, is also the cause of menstrual stomach pain. Fourthly, some stomach pains may be related to diseases. Patients with uterine fibroids, endometriosis and adenomyosis may easily lead to menstrual pain.