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Progesterone Opposition

Meaning

Progesterone Opposition is the essential biological function of progesterone to counteract and neutralize the proliferative and growth-stimulating effects of estrogen on certain tissues, most notably the endometrium, which is the lining of the uterus. This antagonistic action is a cornerstone of reproductive physiology, ensuring the cyclical shedding of the endometrium during the menstrual cycle and preventing pathological overgrowth. Clinically, this principle necessitates the co-administration of progesterone or a progestin alongside estrogen therapy in women with an intact uterus to mitigate the risk of endometrial hyperplasia or cancer.