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Why does menstruation stop when ovarian function declines?

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Menstruation is the result of a cyclical process driven by the ovaries, which secrete estrogen and progesterone to prepare the endometrium (the uterine lining) for potential pregnancy.12

During a normal menstrual cycle, these hormones cause the endometrium to thicken and become vascular. If an ovum is not fertilized, the corpus luteum degenerates, leading to a sharp decrease in estrogen and progesterone levels. This hormonal withdrawal causes the constriction of uterine arteries, which interrupts the supply of oxygen and nutrients to the endometrium, causing it to slough off as menstrual bleeding.21

Menopause occurs when the ovaries lose their function, characterized by a significant depletion of follicles. Because the ovaries no longer produce sufficient levels of estrogen and progesterone to stimulate the cyclic growth and subsequent shedding of the endometrial lining, menstruation permanently ceases.312