Puberty usually starts between the ages of 8 and 13 and lasts a few years. It may start earlier in girls who are overweight, or later in girls who are very athletic or thin. If you are 12 and haven’t started developing breasts or are 15 and haven’t gotten your period, your doctor will probably want to examine you to make sure everything’s OK.
During puberty, your body releases hormones that stimulate your ovaries to start producing the female hormone estrogen. Gradually, a girl’s body starts changing into a woman’s body. But these surging hormones can also make your mood go up and down — and sometimes it may seem as if your body is out of control.
Most girls experience growth spurts early in puberty, while most boys have them later in puberty. That’s why many girls are taller than boys in middle school.
Along with gaining curvier hips, your breasts grow during puberty. Inside them, a network of milk ducts develops. This is your body’s way of preparing you to nurse a baby when you’re older.Breast development is one of the changes that stress girls out the most.