Menopausal transition is a progressive endocrinologic decline in hormone levels that takes a reproductive-aged woman from regular, cyclic menses to her final menstrual period, ovarian senescence, and beyond. With medical advancements, average life expectancy has risen, and most healthy women can now expect to live at least one third of their lives in the menopause. Life expectancy for women in 2014 approximated 81 years (Arias, 2019). Specifically, by 2050, approximately 47 million women will be aged 45 to 64 years (U.S. Census Bureau, 2017). Importantly, menopausal transition and years spent in the postmenopausal state bring with them issues related to quality of life and disease prevention and management.
Menopause refers to a point in time that follows 1 year after the complete cessation of menstruation, and the postmenopause describes years following that point. The average age of women experiencing their final menstrual period (FMP) is 51.5 years, but a halt to menses from ovarian failure may occur at any age. Cessation before age 40, termed premature ovarian insufficiency, is associated with elevated follicle-stimulating hormone (FSH) levels, and its variable causes are described in Chapter 17 (p. 375). Menopausal transition (MT), often referred to as perimenopause or climacteric, refers to the late reproductive years, usually late 40s to early 50s (Harlow, 2012; Santoro, 2005). Characteristically, MT begins with menstrual cycle irregularity and extends to 1 year after permanent cessation of menses. This reproductive aging with loss of follicular activity progresses within a wide age range (42 to 58 years). The average age at its onset is 47 years, and MT length was found in the multiethnic Study of Women Across the Nation (SWAN) to range from 4 to 8 years. MT lasted longer in women who had earlier transition onset and in those who smoked (Paramsothy, 2017).
As chronologic age is an unreliable indicator, classification of reproductive aging has been proposed. The first was developed in 2001 and updated in 2012 at the Stages of Reproductive Aging Workshop +10 (STRAW) (Harlow, 2012). These staging criteria are guides rather than strictly applied diagnoses. For example, every stage may not manifest in all women, or a stage may present out of the expected sequence. Moreover, the age range and duration of each stage varies among individuals.
In the STRAW system, the anchor stage is the FMP (Fig. 22-1). Five stages precede and two stages follow the FMP. Stage +1a is the first year after FMP, stage +1b reflects years 2 to 5 postmenopause, and stage +2 refers to the ensuing later postmenopausal years, in which estrogen levels continue to decline.
The stages of reproductive aging. ∆ = change; AMH = antimüllerian hormone; AFC = antral follicle count; FSH = follicle-stimulating hormone. (Redrawn with permission from Harlow SD: Executive summary of ...