What about aunt?

Menstruation is accompanied by periodic changes in the ovary and the performance of the endometrial periodic shedding and bleeding. Regular menstrual performance is a sign of reproductive maturity. Female first menstrual flow called menarche, an important sign of puberty. Menstruation suggests that the ovary produces estrogen enough to make the endometrium proliferate, estrogen reaches a certain level, and there are obvious fluctuations, causing endometrial shedding, that is, performance of menstruation. Menstruation is an important physiological phenomenon for women in reproductive period. Pay attention to hygiene during menstruation and change sanitary napkins frequently. For prolonged menstruation, excessive menstruation, frequent menstruation, menstrual cycle irregularities, see a doctor in time.