Oestrogen levels fluctuate and decline in a female’s lifetime. Oestrogen is produced by the developing follicle in the ovary. When the follicles begin to reduce in number and quality, oestrogen levels fall. When these levels fall to a certain level there is no longer stimulation of the lining of the uterus (endometrium) and the menstrual bleed stops.
However, several years up until that time there are symptoms consistent with falling levels of oestrogen due to the fluctuations. Even after the menopause oestrogen levels can continue to fall for some years and therefore menopausal symptoms may persist or HRT adjustments may be needed to keep pace with the natural fall in production of oestrogen.
Falling levels of oestrogen - such as premenstrually and in the perimenopause or a permanent lack of oestrogen such as in the post menopause, can result in different groups of symptoms depending upon the individual -