Menstruation is a cyclical change in which the endometrium proliferates, secretes, and sheds periodically. And the endometrium is regulated by changes in estrogen and progesterone so that cyclic bleeding occurs.
Women with normal menstruation experience endometrial proliferation on days 5-14 of menstruation. At this time, under the action of estrogen, the surface epithelium, glands, mesenchyme, and blood vessels of the endometrium show proliferative changes. On days 15-28 of the menstrual cycle, under the action of progesterone and estrogen, the endometrium continues to thicken during the proliferative phase, the glands grow and bend, and secretion occurs.
On days 5-28 of the menstrual cycle, the lining of the uterus gradually thickens and reaches approximately 10 mm before the onset of menstruation. on days 1-4 of the menstrual cycle, with the withdrawal of estrogen and progesterone, the lining of the uterus disintegrates and falls off, and menstruation occurs.
Women who experience menstrual abnormalities need to seek prompt medical treatment.