The cause of stomach cramps on the 15th day of the menstrual cycle is considered to be related to ovulation, gynecological inflammation, gastrointestinal diseases and so on. 1. Ovulation: the 15th day of the menstrual cycle, may be in the ovulation period, ovulation, with the discharge of eggs, follicular fluid will gradually enter the pelvis, stimulate the pelvic peritoneum, some women may have a slight pain discomfort, so this type of patients will have the phenomenon of the 15th day of the menstrual cycle, stomach drop pain. 2. Gynecological inflammation: women’s menstrual cycle on the 15th day of the tummy drop, can not be ruled out due to pelvic inflammatory disease or endometritis and other factors, mainly due to the lack of attention to hygiene, secondary bacterial infections caused by the stimulation of inflammatory substances, resulting in patients with a tummy drop. 3. Gastrointestinal diseases: 15 days of the menstrual cycle and stomach pain can not be ruled out and gastrointestinal diseases, such as eating cold spicy or unclean food, may cause gastrointestinal smooth muscle spasms, which in turn produces a hidden pain in the stomach area, may be accompanied by symptoms of diarrhea. Women in the menstrual cycle after the 15th day of the small stomach pain, should be with the doctor to clarify the specific causes, and then do targeted treatment and treatment, should avoid unauthorized use of medication in order to avoid delaying the condition.