It is normal for a 10 year old girl to have a discharge. At the age of 9 to 12, girls begin to develop secondary sexual characteristics, which means that the ovaries begin to secrete a certain amount of estrogen and progesterone, but because the ovaries are very immature, the amount of hormone secretion is not very stable. Female discharge is caused by the rise of estrogen levels in the body, which leads to the secretion of a certain amount of mucus from the endometrium, cervix and vagina along with the discharge of shed epithelial cells to form leukorrhea. Normal leukorrhea is white or milky, sticky and odorless, and its nature will change as the amount of hormone secretion in the body changes. If the leucorrhea appears yellow or yellow-green, bean curd-like or watery leucorrhea with a distinct odor, it indicates the presence of pathogenic bacteria infection and requires prompt medical attention.