Your best friend, Julia, has it. Even Karen, the 10-year-old down the street, has it. So why don't you have your period yet? A girl's period, also known as menstruation, begins after she has reached ...

You can stop your period with continuous cycle pills, an IUD, shots, patches, or vaginal rings. To delay your period, you can skip your placebo week of birth control and start a new pack. You can't ...