The term “amenorrhea” describes a prolonged time period without menstruations during reproductive years, when regular menstruations should be the norm in women. Though menstruations are supposed to follow a regular pattern, every woman experiences some irregularities on some occasions. These irregularities are reflections of the sensitivity of the reproductive hormonal axis that controls the menstrual cycle to environmental factors, like travel, stress, disease, etc. Such brief irregularities in menstruation are, however, not what the term “amenorrhea” describes. A menstrual irregularity becomes amenorrhea only once it is prolonged, usually demonstrating no menstrual flow for at least three months.
Such complete cessation of menstrual flow can have many different reasons, which are relatively easy to remember if one just considers what is needed in order for a woman to menstruate: First of all, the correct anatomy must be present and it must function appropriately. Since menstrual flow represents shedding of the superficial layer of the endometrium, there will be no menses if there is no endometrium or if there is no uterus. Consequently, amenorrhea can be an early and typical sign of the so-called Asherman’s syndrome, which means that the endometrial cavity is obliterated by fibrous scar tissue, thus not allowing endometrium to regenerate and shed every month. Women will, obviously, also stop menstruating if the uterus is surgically removed. Finally, amenorrhea may set in if the outflow of menstrual blood from the uterus is obstructed. This can happen in cases of so-called cervical stenosis as a consequence of excessive fibrosis in the cervix, scarring after surgery or injury to the cervix or even an inappropriately located myoma (fibroid)that occludes the cervical outlet.
Just as easily, amenorrhea can have hormonal rather than anatomical causes. As already noted above, menstrual flow happens every month because of hormonal changes that affect the endometrium within the endometrial cavity and, ultimately, every month leads to the shedding of the superficial layer of this endometrium. In order for shedding to occur, the endometrium, first, must significantly expand in thickness every month. This so-called endometrial proliferation is the result of typical cyclic hormonal changes in women with regular menstruation, controlled by the hypothalamus, which affects the pituitary gland, which, in turn, affects all peripheral hormone-producing glands, including the ovaries. And this reproductive hormonal axis, as already noted, is very sensitive to the environment.
With significant changes in regularity of menstrual flow and, especially, should real amenorrhea set in, a doctor’s visit is indicated. Amenorrhea may have no significant meaning for an individual’s well-being (and is, of course, also the principal sign of menopause) or may be a sign of significant problems. Hormonal and anatomic changes can, of course, present in a large variety of different ways and based on different underlying mechanism. Simply having too little body fat (as often seen in female athletes) may prevent menses from occurring. By just gaining a few pounds, menses may then return in a completely normal fashion. Medications may also prevent menses. The classical example are birth control pills. If taken without interruption (or sugar pills in between), a woman will cease menstruating. Once she stops the pills, she usually will, however, quickly return to normal menstruation if her hormonal reproductive axis is intact and he anatomy is normal.
Amenorrhea, therefore, does not mean that something is necessarily very wrong; during reproductive years, however, it certainly means that it is time to see a gynecologist, reproductive endocrinologist of fertility specialist for a check-up.
This is a part of the March 2019 CHR VOICE, updated on November 2019.
Norbert Gleicher, MD, leads CHR’s clinical and research efforts as Medical Director and Chief Scientist. A world-renowned specialist in reproductive endocrinology, Dr. Gleicher has published hundreds of peer-reviewed papers and lectured globally while keeping an active clinical career focused on ovarian aging, immunological issues and other difficult cases of infertility.
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