Progesterone is normally perscribed with estogen to avoid “estrogen dominance.” It decreases the risk of endometrial cancer in women who are receiving estrogen.

Progesterone and synthetic progestins have generally indistinguishable effects on endometrial tissue (i.e., both prevent hyperplasia of the lining of the uterus, which can progress to endometrial cancer). However, in other body systems, natural progesterone has diffent effects than synthetic progestins. Progesterone has a calming effect and is taken in the even promoting better sleep.