The menopause literally means the end of menstrual periods. The climacteric is the whole period of time when ovarian function is declining; that is, egg production is ceasing and along with it, production of the female sex hormones; oestrogen and progesterone. The climacteric is the winding-down process, just as puberty is the winding-up.
At the beginning of puberty, the ovaries start to produce oestrogen in response to gonadal stimulating hormones produced by the pituitary gland, which in its turn has been stimulated by the hypothalamic region of the brain. The age of puberty varies from nine to fifteen, or more. What turns the process on is unknown, but an early onset tends to run in families. Climate influences it, as do emotional state, body weight, and regular sleep. Puberty is signalled by a spurt in growth and breast enlargement. The uterus, vulva and vagina enlarge, and hair appears on various areas of the body.
At a variable time after this, ovulation (release of an egg or ovum) occurs, and progesterone, the second hormone, is produced, which, with oestrogen, is responsible for menstruation. Each month ovulation followed by periods is the normal process in a woman’s life, the normal menstrual cycle. The pituitary gland produces follicule-stimulating hormone, which causes the ovarian-follicles (sites where the eggs develop) to ripen and release oestrogen. One egg follicle goes on to mature in about two weeks, but the remainder do not usually develop. The pituitary then puts out a second hormone, or luteinising hormone (LH), and the egg is released. The egg passes down the fallopian tube to the uterus, leaving behind the ruptured egg follicle, which develops into the corpus luteum and produces progesterone. The lining of the uterus has been built up by the oestrogen ready to receive a fertilised egg, but if it is not fertilised, the lining is shed and menstruation results.
At menopause, ovarian production fails, and menstruation no longer occurs. A few years before the menopause, however, ovarian function has been reduced and no progesterone is produced, so regular periods become irregular, and they may be light or heavy.
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