EFFECT OF PROGESTERONE ON THE NORMAL HUMAN MENSTRUAL CYCLE

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Abstract
A correlation was established between the effects of progesterone on the menstrual cycle of the baboon and the normal human [female] when this hormone was administered on the 8-10th day of the cycle. In the human [female], 3 varying effects of progesterone are described: lengthening of the cycle, production of intracyclic hemorrhage without postponing the appearance of normal menstrual bleeding and shortening of the cycle by precipitation of premature bleeding, and initiation of a completely new cycle. In the baboon intracyclic hemorrhage was not produced with progesterone but the cycle could be lengthened or shortened. 7 times as much progesterone was required by the human [female] to produce alterations in the cycle not attended by bleeding. The human being can be described as being 7 times more resistant to progesterone than the baboon. The amt. of progesterone necessary to cause premature bleeding in the human [female] is equal to or may be twice as much as that required to produce comparable effects in the baboon. The dosage necessary for this purpose was 20-30 mg. of progesterone; in the baboon it was 15-20 mg. Progesterone is effective in the human [female] for the same time as in the baboon, namely, 60-96 hrs. In the baboon, depending on the dose, progesterone either arrests or completely inhibits the action of the ovaries in their production of the estrogenic hormone; in the human [female] in most cases it seems that the drug inhibits the ovarian rhythm completely and, after the period of progesterone effectiveness, the released ovaries, without being preceded by hemorrhagic discharge from the uterus, initiate a new cycle. The onset of bleeding, when it occurs after progesterone withdrawal in either the baboon or the human [female] is twice as rapid as after estrogen withdrawal. Attention is drawn to 3 points of clinical importance: the normal human [female] is very resistant to progesterone; the effects of progesterone wear off after 60-96 hrs.; and hypomenorrhoea and polymenorrhoea may be due to abnormal corpus luteum activity.