http://youngwomenshealth.org/2010/04/21/menstrual-periods/ http://youngwomenshealth.org/2010/04/21/menstrual-periods/ http://youngwomenshealth.org/2010/04/21/menstrual-periods/ Puberty and Your Menstrual Cycle: A Guide for Teens. Puberty and Your Menstrual Cycle: A Guide for Teens. Puberty and Your Menstrual Cycle: A Guide for Teens. Menstrual Periods | Center for Young Women's Health youngwomenshealth.org youngwomenshealth.org get their periods between 21 and 35 days,