Menopause & Perimenopause: Overview

This page covers definitions, physiology, and the stages of the transition. For symptoms and how the diagnosis is made, see Symptoms, Diagnosis & Assessment. For treatment, see Menopause Treatment: MHT & Non-hormonal. For menopause before 40, see Premature ovarian insufficiency.

Definitions

Menopause is the permanent cessation of menstruation, diagnosed retrospectively after 12 months of amenorrhoea.

The menopause transition (perimenopause) usually starts around age 47. Natural menopause averages age 51. Early menopause means before 45. Premature menopause / POI means before 40.

Physiology

Menopause results from progressive loss of ovarian follicular activity. Oestradiol and progesterone fall, and pituitary FSH rises as negative feedback weakens. Most symptoms — vasomotor, genitourinary, mood, sleep — relate directly to this oestrogen deficiency.

Stages

• Premenopause — up to 5 years before the last menstrual period.
• Perimenopause — early menopausal symptoms with a changing menstrual cycle. Cycle length may vary by about 7 days in the early transition (e.g. a 28-day cycle becomes 21); the late transition can show two or more skipped cycles, with erratic bleeding — prolonged, or scanty and interspersed with regular ovarian activity.
• Menopause — the last menstrual period itself.
• Postmenopause — beginning 12 months after the last menstrual period.

How common are symptoms

Menopausal symptoms occur in around 75% of women and are moderate to severe in 28% — they may start during perimenopause and last, on average, 7 to 10 years, so this is not a brief transition for most women. More than half of women at midlife have frequent hot flushes and sweats lasting up to 7 to 8 years and persisting roughly 4.5 years after the final period. 42% of women aged 60–64 still experience vasomotor symptoms, with 6.5% moderate to severe.