Dysfunctional uterine bleeding is caused by abnormal ovulation, resulting in abnormal uterine bleeding. In adolescence, due to the immature development of the gonadal axis, most do not have normal ovulation. Although there is follicular development, the absence of ovulation means that the endometrium is not affected by progesterone. Therefore, when estrogen breakthrough bleeding occurs, it may manifest as irregular vaginal bleeding, excessive menstrual flow, or prolonged menstrual periods, which is the blood supply during adolescence. In menopause, women can also experience dysfunctional uterine bleeding due to ovarian failure, immature follicle development, abnormal ovulation, or the absence of ovulation, which can all cause irregular vaginal bleeding.