Why is your period coming?

Menstruation is the menstrual period, with the ovarian cycle ovulation and estrogen, progesterone changes, the endometrium showed periodic shedding and bleeding, this is menstrual cramps. Endometrial hyperplasia period for the menstrual cycle 5 to 14 days, is also the development of follicles, mature stage, under the action of estrogen, endometrial hyperplasia changes. The secretion period of the endometrium is the 15th to 28th day of the menstrual cycle, which is also the luteal phase of the ovarian cycle. The luteal phase secretes estrogen and progesterone to continuously thicken the endometrium. The menstrual period is the 1st to 4th day of the menstrual cycle. The luteal degeneration, estrogen and progesterone drop sharply, vasospasm contraction, resulting in ischemia, necrosis, exfoliation, and shedding of endometrial fragments and blood from the vagina. That is, menstruation.