Progesterone is a naturally occurring progestin or a synthetic form of the naturally occurring female sex hormone, progesterone. In a woman's normal menstrual cycle, an egg matures and is released from the ovaries (ovulation). The ovary then produces progesterone, preventing the release of further eggs and priming the lining of the womb for a possible pregnancy. If pregnancy occurs, progesterone levels in the body remain high, maintaining the womb lining. If pregnancy does not occur, progesterone levels in the body fall, resulting in a menstrual period. Progesterone tricks the body processes into thinking that ovulation has already occurred by maintaining high levels of the synthetic progesterone. This prevents the release of eggs from the ovaries.

Therapeutic Progesterone is a synthetic form of the endogenous hormone progesterone. Progesterone binds to the progesterone receptor, resulting in dissociation of heat shock proteins, receptor phosphorylation, and transcription activation through direct or indirect interaction with transcription factors. This agent exerts inhibitory effects on estrogens by decreasing the number of estrogen receptors and increasing its metabolism to inactive metabolites. Progesterone induces secretory changes in the endometrium, decreases uterine contractility during pregnancy, and maintains pregnancy.

Produced in the corpus luteum and by the placenta, as an antagonist of estrogens. Promotes proliferation of uterine mucosa and the implantation of the blastocyst, prevents further follicular development.