UNDERSTANDING THE MENOPAUSE: THE PERI-MENOPAUSAL CYCLE
During the fertile years there is a gradual depletion of ovarian follicles, and hence the egg cells they contain. This process generally becomes more rapid from the age of 35. At the menopause only a few eggs remain. With the depletion of the follicles, the level of fertility is reduced and oestrogen deficiency begins. As the number of granulosa cells in the follicles reduces, inhibin production also decreases, very gradually. The level of follicle-stimulating hormone therefore changes little.
By the early forties the number of granulosa cells has decreased to such a degree that the level of inhibin they secrete will have fallen to a critical point; the level of follicle-stimulating hormone now rises. Although the menstrual periods may still be completely regular and no menopausal symptoms are being experienced, the rising follicle-stimulating hormone level represents the beginning of the peri-menopause.
As follicle depletion continues over the next few years the level of follicle-stimulating hormone will fluctuate, causing the menstrual cycle to become irregular. The amount of menstrual flow also alters, being sometimes lighter and sometimes heavier. By now the follicle-stimulating hormone will be approaching, or have reached, the point at which the peri-menopause can be said to have begun. Conception is now unlikely to happen. Oestrogen production usually remains near-normal in the early years of the peri-menopause, therefore symptoms associated with oestrogen deficiency, such as hot flushes and vaginal dryness, will not yet be evident. As oestrogen levels fall over the next few years the occasional hot flush, increasing tiredness and perhaps dizziness will occur, and menstrual periods may become more irregular with episodes of heavy bleeding.
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Womens health