The age of first menstruation in women is usually between 13 and 14 years of age, but may be as early as 11 or as late as 16. Menstruation refers to the periodic shedding of the uterine lining and bleeding that accompanies the cyclical changes in the ovaries. The first menstrual period is called menarche. The age of menarche is an important indicator of female pubertal development. The appearance of regular menstruation is an important sign of reproductive maturity. The age of menarche is influenced by hereditary factors and is also related to economic level and nutritional status. The first menstrual period usually occurs between the ages of 13 and 14, but may occur as early as 11 or as late as 16. The presentation of the first menstrual period is closely related to the physical growth of puberty. The physical form, level of functioning, and development of secondary sexual characteristics of women who have already menstruated are significantly greater than those of girls of the same age who are not yet menstruating. After menstruation, women should pay attention to keeping the local area clean and hygienic, change sanitary napkins frequently, and consult a doctor if they feel unwell.