What's wrong with no period?

Menstruation refers to the periodic shedding and bleeding of the endometrium accompanied by periodic changes in the ovary. The establishment and maintenance of normal menstruation depends on neuroendocrine regulation of the hypothalamus, pituitary gland, and ovarian axis, periodic response of the target organ endometrium to sex hormones, and patency of the lower reproductive tract. For fertile women, pregnancy and pregnancy-related diseases such as ectopic pregnancy or trophoblastic tumors should be ruled out first. In addition, there may be hypothalamic causes, such as mental stress, rapid weight loss, anorexia nervosa, exercise amenorrhea. At the same time, there may be ovarian amenorrhea causes, such as premature ovarian failure, polycystic ovary syndrome and other uterine causes, amenorrhea caused by multiple abortions, thyroid dysfunction, adrenal cortical tumors.