What does period mean?

Menstruation is a clinical term for menstruation. Menstruation refers to the periodic shedding and bleeding of the endometrium accompanied by periodic changes in the ovary. Regular menstruation is an important sign of reproductive maturity. The first menstrual flow is called menarche. Menarche is mostly between 13 and 14 years old, but may be as early as 11 or as late as 16 years old. Menarche age in recent years there is a trend in advance, menstrual blood is dark red, in addition to blood and endometrial debris, cervical mucus and shedding vaginal epithelial cells.