The stomach pain on the fourth day of menstruation may be due to the poorer resistance and lower immunity of the body during menstruation. If you do not pay attention to the cleanliness and hygiene of the vulva during menstruation, it may cause pelvic inflammatory disease and pelvic infection, which will lead to menstrual stomach pain. If the patient does not pay attention to local heat preservation during menstruation, getting cold, getting cold or eating food just taken out of the refrigerator, such as chilled drinks or ice cubes, it may cause stomach pain and dysmenorrhea during menstruation. If the patient suffers from mental shock, anger or change in mood during menstruation, etc., menstrual stomach pain may also occur.