Menstruation disrupts almost every bodily system in most women

Evidence

This complex process, whose details are still quite mysterious, sets the whole body in motion as it is accompanied by hormonal secretions that act on the thyroid and pituitary glands, the central and peripheral nervous systems, and thus on all the organs. Almost all women—more than 85 percent—show signs of distress during this period. Blood pressure rises before the beginning of the flow of blood and then falls; the pulse rate and often the temperature increase; there are frequent cases of fever; the abdomen is painful; there is often constipation and then diarrhea, an increase in the liver volume, urea retention, albumin deficiency, or micro albumin; many women have hyperemia of the pituitary gland (sore throat), and others complain of auditory and visual problems; there is a rise in perspiration secretions accompanied by a sometimes strong sui generis odor at the beginning of and often throughout the menstrual period. Basal metabolism increases. The number of red blood cells decreases; however, the blood carries substances usually kept in reserve in the tissues, in particular calcium salts; these salts act on the ovary, on the thyroid that is overactive, and on the pituitary gland that regulates the metamorphosis of the activated uterine tissue; this glandular instability weakens the nervous system: the central nervous system is affected, often causing headaches, and the peripheral nervous system overreacts: the automatic control by the central nervous system is reduced, which relaxes the reflexes and the convulsive complexes and is manifested in great mood changes: woman is more emotional, nervous, and irritable than usual and can manifest serious psychological problems. This is when she feels most acutely that her body is an alienated opaque thing; it is the prey of a stubborn and foreign life that makes and unmakes a crib in her every month; every month a child is prepared to be born and is aborted in the flow of the crimson tide; woman is her body as man is his, but her body is something other than her. — Simone de Beauvoir, The Second Sex, 97