Definition and Stages
Menopause Definition
Natural menopause is defined as the permanent cessation of menstruation due to the loss of ovarian follicles, resulting in hypoestrogenism and the end of reproductive potential. Menopause is retrospectively diagnosed after 12 consecutive months of amenorrhea in the absence of any other pathological or physiological cause. Individuals who do not menstruate regularly (for reasons such as hysterectomy, anovulation, or medication-induced amenorrhea) also go through menopause when their ovarian reserve declines, but their final menstrual period is not always known. The average age of menopause in Canada is 51 years, however, typically ranges between 45 – 55 years. Menopause can also be induced either surgically (e.g. bilateral oophorectomy) or medically (e.g. chemotherapy, pelvic radiation, gonadotropin modulators) and is often associated with more abrupt and severe menopause symptoms due to rapid decline in estrogen.
Early menopause is defined as menopause before the age of 45 years and premature (also known as premature ovarian insufficiency) before the age of 40 years.
Stages of Menopause
The time leading up to the menopause is called perimenopause and any time after menopause is termed postmenopause. The Stages of Reproductive Aging Workshop (STRAW+10) is the gold standard for characterizing the stages of reproductive aging.1 It uses menstrual cycles and hormone levels to define the different stages. Below is a summary of the different stages captured in the STRAW+10:
Pre-menopause: the time before any menopausal symptoms begin.
Perimenopause: The transitional phase leading up to menopause is often associated with menopause symptoms and/or changes in the menstrual cycle. The term menopause transition is also sometimes used interchangeably however, perimenopause also includes up to the 12 months after the final menstrual period when menopause is diagnosed. Perimenopause can occur anywhere from 4 – 8 years before the menopause and in some it can be 10 years or longer. Menopause symptoms can occur even before menstrual cycle changes, and menstrual cycle changes can occur without menopause symptoms. This is a time of hormonal fluctuations which can lead to menopause symptoms and menstrual irregularities. Pregnancy is still possible during this stage therefore contraception may be needed. This stage is defined as early and late stages:
Early perimenopause–The start of menstrual cycle variability ( ≥ 7 days variability in cycle length) and/or menopause symptoms
Late perimenopause–Skipped cycles of 60 days or greater of amenorrhea
Menopause: Defined as 12 consecutive months without a menstrual period.*
Postmenopause: Any time after the menopause.
*Of note, this definition does not apply to individuals who have amenorrhea due to other factors such as hysterectomy, endometrial ablation, or have medication induced amenorrhea (ie progestin-releasing intrauterine device (IUD), hormonal contraception).
Details of the STRAW+10 can be found here.