“It can be caused by dysfunctioning of the pituitary gland, ovaries, uterus, or hypothalamus, by surgical removal of the ovaries or uterus, by stress or other emotional factors, or by inadequate nutrition. Often a hormone imbalance is responsible for amenorrhea. Frequently the body’s level of gonadotropin-releasing hormone is low. This hormone secondary is needed to control a woman’s menstrual cycle and ovulation. Analogies can be drawn between decreasing GnRH levels and excessive exercise, weight loss or weight gain, stress, or discontinuation of the birth control pill. Also, women with anorexia and female athletes have an increased incidence of amenorrhea.
“A hormone imbalance and amenorrhea can also result from breast-feeding, ovarian cysts, premature ovarian failure, problems with the adrenal glands, thyroid conditions, tumors, anorexia, or other medical conditions. But use of the birth control pill at a young age does not seem to be a factor in amenorrhea.”