Progesterone: a pivotal hormone at menstruation

The human endometrium is exposed to repeated inflammation every month, culminating in tissue breakdown and menstruation. Subsequently, the endometrium has a remarkable capacity for efficient repair and remodeling to enable implantation if fertilization takes place. Endometrial function is known to be governed by the ovarian hormones estradiol and progesterone. This review paper focuses on hormonal control of the cyclical tissue injury and repair that takes place in the local endometrial environment at the time of menstruation. Progesterone levels decline premenstrually as the corpus luteum regresses in the absence of pregnancy, and estradiol levels increase during the postmenstrual phase. The functional impact of these significant changes is discussed, including their immediate and downstream effects. Finally, we examine the contribution of aberrant endometrial function to the presentation of heavy menstrual bleeding and identify potential therapeutic targets for the treatment of this common gynecological problem.