Ball-and-stick model of the progesterone molecule, C21H30O2.

Both males and females produce the hormone progesterone. This hormone, like most other hormones, performs a number of different duties in the body. The most commonly identified process that progesterone is connected with are menstrual cycles. The concentration of progesterone generally indicates what phase of the reproductive cycle a woman is in. The physiological effects of progesterone on males has not resulted in conclusive results. Research articles on this specific topic appear to contradict each other. This, however, can be interpreted as a sign of the very complex nature of progesterone.

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Jynto on Wikimedia Commons