Girls get their first periods during puberty, typically between the ages of 10 and 15, with age 12 being the average, explains KidsHealth. Girls usually begin menstruating about two years after they begin developing breasts. A girl may also notice vaginal discharge six to 12 months before a first period, the growth of pubic hair and the typically subsequent growth of underarm hair.Continue Reading
Once a girl begins her menstrual cycle, it can take a while for her to begin experiencing periods on a regular schedule, and she may go months without another period after her first, KidsHealth explains. As time goes by, a girl's cycle typically normalizes to a length of between 21 and 34 days.
Each girl experiences periods differently. Some periods last as few as two days, while others last a full week. While one girl may experience a great deal of cramping, another may have such minimal discomfort that she hardly remembers she is on her period. If a girl has periods that last beyond a week, needs to change her sanitary pad more often than every one to two hours, experiences unbearable pain, or notices bleeding in between periods, she should consult with her doctor, KidsHealth notes.Learn more about Menstruation