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Physiology of the menstrual cycle and changes in the perimenopause

Research output: Chapter in Book/Report/Conference proceedingChapter

Philip J. Dutton, Janice M. Rymer

Original languageEnglish
Title of host publicationManaging the Menopause: 21st Century Solutions
PublisherCambridge University Press
Pages1-10
Number of pages10
ISBN (Print)9781316091821, 9781107451827
DOIs
Publication statusPublished - 1 Jan 2015

King's Authors

Abstract

Introduction The menopause marks the permanent cessation of menstruation and heralds the transition in a woman's life from a reproductive state to a non-reproductive one. Whilst the average age of this landmark varies slightly across the world, the menopause generally occurs in the early 50s, and is only truly affected by factors such as smoking, and medical and surgical induction of the menopausal state. However, clinical symptoms may precede this, and the physiological changes which occur with the menopausal transition may begin several years prior to the onset of any manifestations. At the heart of the clinical and biochemical changes associated with the perimenopausal period is the depletion of ovarian follicles to a critical level [1–8]. Although the physiology of the normal menstrual cycle has been studied extensively, research concerning the physiological changes of the menopause and their relationship to menopausal symptoms has only begun to make significant advances in the last two decades. The development of a validated staging system has been immensely beneficial in standardizing nomenclature surrounding the menopause, as well as characterizing the changes at each stage in the transition. Despite these developments, there remain considerable gaps in the literature which require further investigation [1–8]. This chapter outlines current knowledge surrounding the staging and physiology of reproductive aging and its relationship to the troublesome symptoms experienced by the majority of women at this challenging stage of their lives. Before discussing this, however, it is important to have a firm grasp of the concepts surrounding the normal menstrual cycle. Premenopausal hormonal regulation of ovarian function The menstrual cycle is controlled by the hypothalamic-pituitary-ovarian axis, which apart from its mid-cycle gonadotropin surge, acts as a negative feedback system, whereby peptide gonadotropins stimulate steroid hormone production in the ovaries, which in turn inhibits gonadotropin secretion, thus allowing cycles to occur [1, 2, 9]. The hypothalamus secretes gonadotropin-releasing hormone (GnRH). This acts on the pituitary gland in a pulsatile manner, which leads to the secretion of the gonadotropins follicle-stimulating hormone (FSH) and luteinizing hormone (LH) [1, 2, 9].

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