Menstruation refers to the physiological phenomenon of periodic bleeding of the uterus, also known as the month, the month water, the month letter and so on。 Girls are usually about 14 years old,menstruate,They shut themselves down around age 49,It lasted about 35 years (now due to nutrition and other reasons),Menarche tends to be earlier,Amenorrhea may recede),This period excludes pregnancy and lactation,It usually comes once a month,One's faith will last forever.,Called menstruation。