The official date is determined retroactively, once 12 months have passed after the last appearance of menstrual blood. The menopause transition typically begins between 40 and 50 years of age (average 47.5). The duration of perimenopause may be for up to eight years. Women will often, but not always, start these transitions (perimenopause and menopause) about the same time as their mother did.In some women, menopause may bring about a sense of loss related to the end of fertility. In addition, this change often occurs when other stressors may be present in a womans life:

Caring for, and/or the death of, elderly parents
Empty nest syndrome when children leave home
The birth of grandchildren, which places people of "middle age" into a new category of "older people" (especially in cultures where being older is a state that is looked down on)Some research appears to show that melatonin supplementation in perimenopausal women can improve thyroid function and gonadotropin levels, as well as restoring fertility and menstruation and preventing depression associated with menopause. Postmenopause
The term "postmenopausal" describes women who have not experienced any menstrual flow for a minimum of 12 months, assuming that they have a uterus and are not pregnant or lactating. In women without a uterus, menopause or postmenopause can be identified by a blood test showing a very high FSH level. Thus postmenopause is the time in a womans life that takes place after her last period or, more accurately, after the point when her ovaries become inactive.
The cyanogenic glycosides in some white clover (Trifolium repens) varieties may influence the Se requirement, presumably because of cyanide from the aglycone released by glucosidase activity in the rumen and inactivation of glutathione peroxidases by the effect of absorbed cyanide on the glutathione moiety.In areas where selenium deficiency in livestock is a concern, selenium (as selenite) may be supplemented in feed. In  some countries, e.g. the US and Canada, such supplementation is regulated. Neonate ruminants at risk of WMD may be administered both Se and vitamin E by injection; some of the WMD myopathies respond only to Se, some only to vitamin E, and some to either. References


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