“When do girls get their first period?”

Usually around age 13.

She should know what she may experience as menarche (onset of periods) may occur at any time for her. Ages 11 to 16 are the norm. She should understand about female anatomy and what causes the menstrual cycle. She should understand after menarche begins basic education about reproduction. She should understand how pregnancy occurs and how it can be prevented. An educated young woman is more likely to make the right choices and not the wrong ones.

William Z. Cohen, M.D., F. A. A. F. P.