At the age of 12, girls are just entering puberty at this time. It takes 1.5-6 years after menarche for adolescent females to establish a stable regulatory mechanism for the menstrual cycle. Because the hypothalamic-pituitary-ovarian axis is not yet mature at this time, follicle-stimulating hormone is at a persistently low level, and although follicles develop, they do not develop into mature follicles. The amount of estrogen synthesized and secreted also fails to reach the threshold for the peak release of luteinizing hormone, so ovulation is impaired. In addition, as adolescent girls are dealing with a period of rapid psychological and physiological changes, emotional changes, emotional vulnerability and developmental deficiencies, the hypothalamus-pituitary-ovary is more susceptible to the influence of internal and external factors leading to ovulation disorders and delayed menstruation. If such a situation occurs, it is a very normal manifestation and there is no need to worry. However, if there is an increase in menstrual flow beyond the normal amount of menstruation, or if there is dripping menstruation beyond the normal menstrual period, you need to visit the hospital at any time. Depending on the condition of the endometrium, medication can be used to regulate menstruation to avoid dysfunctional uterine bleeding, which can cause anemia and hemorrhagic shock.