The reasons for the shortening of the menstrual cycle are: 1. During ovulation, the bleeding may be caused by the rupture of the follicle, the bleeding is relatively small and usually stops in 2-3 days. If the abdominal pain and heavy bleeding require medical treatment, 2, bleeding caused by damage to the endometrium during embryo implantation in early pregnancy, the amount of bleeding is also relatively small and can be confirmed by checking the HCG level. 3, menstrual disorders, women due to the pressure of life, work or their own disorders of sex hormone levels, thus causing the shortening of the menstrual cycle. 4, leakage of sex hormone drugs caused by breakthrough bleeding, common 5.Malignant tumors or polyps in the female genital area can damage the surrounding mucosal tissue and cause bleeding accompanied by the odor of leucorrhea.