Breast development is normal at the age of nine for girls.
There are two peak developmental periods for girls’ breasts, the 1st peak developmental period is between the ages of 9 and 13, and the 2nd peak developmental period is between the ages of 18 and 20. When a girl’s breasts develop at the age of 9, the nipples will initially appear larger, and as the breasts develop, the mammary glands will begin to proliferate, forming a nucleus, and the breasts will feel sore when touched.
When a girl is 13 years old, the fat and milk ducts in the breasts will slowly increase, and from the appearance, the breasts have been obviously bulging, and the breasts are basically mature when the breasts develop to the age of 20.
After a girl’s breasts begin to develop, parents should help the girl choose the right underwear to protect her breasts, because the stage of breast development is different, the underwear chosen will be different.