How does estrogen affect the lining of the uterus during the menstrual cycle?

During the menstrual cycle, estrogen plays a critical role in building and maintaining the endometrium, the mucous membrane lining the uterus.1

Following menstruation, the body enters the proliferative phase, during which the ovaries secrete increasing amounts of estradiol. This hormone stimulates the endometrium to regenerate from the residual basal layer. Under the influence of estrogen, the endometrium increases in size, weight, and vascularity. Specifically, the uterine glands become taller, and the tissue becomes thicker as the cells multiply.231

These estrogen-driven changes are essential for preparing the uterine environment. While estrogen initiates this growth, the subsequent addition of progesterone during the luteal phase further modifies the lining to support potential implantation. If fertilization does not occur, the eventual withdrawal of estrogen and progesterone leads to the constriction of uterine arteries and the subsequent shedding of the endometrial lining during menstruation.432