If you are 12 and haven't started developing breasts or are 15 and haven't gotten your period, your doctor module credibly want to examine you to modify certain everything's OK. It may beginning first in girls who are overweight, or later in girls who are very athletic or thin. Puberty ordinarily starts between the ages of 8 and 13 and lasts a few years. OK, so it's a funny word — but what is puberty, anyway? Puberty say: PYOO-ber-tee is the family for the case once your gathering begins to develop and change as you play from kid to adult.