What reason does girl menstruation defer half month

If the puberty of women after menarche, will often show menstrual delay and menstrual or menstrual volume changes, are normal phenomena, do not do intervention. Adolescent women due to the imperfect development of the HPO axis, no ovulation situation, may show no regular menstruation, are normal phenomena. If after puberty, there is already regular menstruation, and then show menstrual delay, mainly considering the mental stress, learning pressure or weight loss, etc., the impact on the hypothalamus, causing menstrual delay. Can eat progesterone to urge menstruation, you can also continue to observe and wait. However, it is also necessary to investigate the menstrual delay caused by polycystic ovary syndrome.