The World Health Organization defines the age range of puberty as beginning at age 10 and ending at age 20. Adolescence is the beginning of a woman’s life cycle with the gradual development of reproductive organs and functions. During this period, physical and psychological development is a critical time in a woman’s life. During adolescence, physical health care should be carried out, and even more attention should be paid to the psychological aspect. Due to the development of sexual functions and hormonal effects, adolescents are in the period of sexual emergence, and if they are not properly guided, they may have distortions and mistakes in their psychology and behavior, such as sexual perversion, premarital sex, unmarried pregnancy, and unmarried abortion, which have become social problems in today’s world. The first menstruation is one of the important indicators of female pubertal development and is an important milestone in the sexual development of girls. The age of menarche is related to the economic level, nutritional status and regional distribution. It usually occurs between the ages of 11 and 16. If you are over 18 years old and have not yet menstruated, you may have abnormalities in your reproductive organs and should go to the hospital for examination as soon as possible. Breast development starts at the age of 10~11 years old, which is usually 2 years earlier than the first menstruation. If you have nipple invagination, nipple overflow, or breast lumps you should see a doctor. During adolescence, attention should be paid to proper nutrition, prevention of menstrual disease, prevention of accidents and attention to menstrual hygiene.