It is generally normal for girls to menstruate at the age of 13. The first menstrual period for girls usually occurs between the ages of 11 and 16, with most girls between the ages of 12 and 14. A girl’s menstruation is influenced by ovarian function, physical condition, genetic factors and so on. The fact that a girl menstruates at age 13 indicates that her sexual reproductive organs are maturing, which is usually normal. After the girl 13 years old to menstruation, due to the ovarian function is not perfect, may lead to scanty menstruation, irregular menstruation, or even functional uterine bleeding phenomenon, with the gonadal axis of the development of maturity, menstruation will tend to be regular. Normally, we should insist on exercising, ensuring a balanced diet and nutrition, and regular rest and relaxation. If the girl 13 years old menstruation after the discomfort symptoms, please timely hospital consultation, follow the doctor’s prescription symptomatic treatment.