Hormonal changes and biomarkers in late reproductive age, menopausal transition and menopause

This chapter describes current definitions of the climacteric, perimenopause, menopausal transition and menopause, and discusses the 2001 Stages of Reproductive Aging (STRAW) criteria in relation to more recently proposed categorization criteria for reproductive aging. Data from endocrine studies on women throughout the menopausal transition are discussed from earliest to most recent. The earlier studies focused on the changes in levels of steroid hormones and gonadotrophins, and established that follicle-stimulating hormone undergoes the first detectable change while menstrual cycles remain regular. Erratic and less predictable changes in steroid hormones follow, especially with the onset of irregular cycles. Later serum hormone studies on the inhibins and anti-Mullerian hormone established that diminishing ovarian follicle number contributes to the endocrine changes with advancing reproductive age. A classification system of cycle types incorporating all available endocrine data and their associated menstrual cycle patterns is proposed, and the application of biological markers as diagnostic tools for reproductive staging is discussed.