The stages explained
Perimenopause: typically 40s, sometimes late 30s
Perimenopause begins years before the final menstrual period. Ovarian function becomes irregular — cycles may lengthen or shorten, ovulation becomes less reliable, and oestrogen and progesterone levels begin fluctuating more widely. This is when most symptoms first appear, often before women (or their doctors) attribute them to hormonal change.
Common perimenopausal symptoms include: irregular periods, vasomotor symptoms (hot flushes, night sweats), sleep disturbance, mood changes (anxiety, irritability, low mood), brain fog, reduced libido, joint aches, and changes in skin and hair.
Menopause: average age 51 in the UK
Menopause is technically defined as 12 consecutive months without a menstrual period. The average age in the UK is 51, though the normal range is 45–55. Early menopause (before 45) affects approximately 5% of women; premature ovarian insufficiency (POI, before 40) affects approximately 1%.
Post-menopause: for the rest of life
After menopause, oestrogen levels stabilise at a new, much lower baseline. Vasomotor symptoms often improve over time, but the longer-term effects — accelerated bone loss, cardiovascular risk changes, and changes in cognitive and genitourinary function — continue.
Many women experience significant perimenopausal symptoms for years before receiving appropriate assessment or treatment. Perimenopause can begin in the late 30s — when hormonal change may not be the first explanation considered by either patient or clinician.
Long-term health implications
Bone density
The rapid oestrogen decline of menopause removes a key restraint on osteoclast activity. Bone density can fall by up to 2–3% per year in the first 5–10 years post-menopause — making this the period when osteoporosis risk increases most sharply.
Cardiovascular risk
Pre-menopausal oestrogen confers cardiovascular protection — women have lower rates of heart disease than men until menopause, after which rates converge over the following decade.
Cognitive function
The brain is sensitive to oestrogen. Many women report cognitive changes during perimenopause ('brain fog', memory lapses), and oestrogen loss is being investigated for its potential role in Alzheimer's risk.
Management options
Hormone replacement therapy (HRT)
Modern HRT (particularly body-identical hormones) is now the recommended first-line treatment for menopausal symptoms by both NICE and the British Menopause Society — with a more favourable benefit-risk assessment than the older combined synthetic HRT that drove concerns following the WHI study.
The decision whether to use HRT is individual and should involve discussion of personal risk factors with a GP or menopause specialist.
NICE recommends offering HRT to women with menopausal symptoms after discussing risks and benefits. For women under 60 without specific contraindications, the evidence suggests the benefits of HRT for symptom relief, bone protection and cardiovascular protection outweigh the risks for most women.
Menopause stages at a glance
| Stage | Typical Age | Key Hormonal Change | Common Symptoms |
|---|---|---|---|
| Late reproductive | Late 30s–40s | Subtle FSH rise; irregular cycles beginning | PMS changes, cycle irregularity |
| Early perimenopause | 40s | Oestrogen fluctuating; progesterone declining | Hot flushes, mood changes, sleep disruption |
| Late perimenopause | Late 40s–early 50s | Oestrogen falling; cycles very irregular | Increasing symptom intensity |
| Menopause | ~51 (UK average) | Oestrogen at new low baseline | 12 months no periods — diagnosis point |
| Post-menopause | 51+ | Stable low oestrogen | Bone loss, CV risk changes, genitourinary symptoms |
Frequently asked questions
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