Precocious puberty is when a child's body begins changing into that of an adult (puberty) too soon. Puberty that begins before age 8 in girls and before age 9 in boys is considered precocious puberty.Puberty includes rapid growth of bones and muscles, changes in body shape and size, and development of the body's ability to reproduce.The cause of precocious puberty often can't be found. Rarely, certain conditions, such as infections, hormone disorders, tumors, brain abnormalities or injuries, may cause precocious puberty. Treatment for precocious puberty typically includes medication to delay further development. Breast development,pubic or underarm hair development, rapid height growth — a growth "spurt",start of menstruation (her period),acne,"mature" body odor.