Growth and Development When a girl enters puberty, many changes occur….her hips widen, her menstrual cycle begins, and hair grows on her legs and under her arms. Gynecological Conditions Common conditions that may affect teen girls include painful periods, premenstrual syndrome, and vaginitis. Adolescent Health Problems Weight issues are common for teens—some adolescents struggle with obesity, and others with eating disorders that leave them too thin. Adolescent Sports Injuries Estrogen appears to affect a female athlete's ligaments, making them more relaxed and boosting the risk for injury.