Perimenopause and menopause: what is actually happening

Menopause is a single day: the point twelve months after your last period. Everything leading up to it, often several years, is perimenopause. Most of the symptoms people call menopause actually belong to perimenopause, which is why they can start while your periods are still coming.

This article explains what is happening to your hormones, why the timeline matters, and what counts as normal.

The hormones behind it

Your ovaries produce oestrogen and progesterone, the two hormones that drive the menstrual cycle. From your late thirties onwards the number of egg-containing follicles in the ovaries falls, and the hormones they release start to fluctuate and then decline. Oestrogen does not switch off smoothly. In perimenopause it swings, sometimes higher than before, sometimes very low, often within the same month. Those swings, rather than a steady fall, are what produce the unpredictable symptoms.

Perimenopause: the years that get missed

Perimenopause usually begins in the mid-forties, though it can start earlier. The first sign is often a change in your periods: closer together, further apart, heavier, lighter, or simply less predictable. Around this, the familiar symptoms appear: hot flushes, night sweats, disturbed sleep, low mood, anxiety, brain fog, joint aches, and changes in libido.

The reason this stage is so often missed is that periods are still happening. A woman of forty-six with regular bleeds and new anxiety may not connect the two, and neither may the first clinician she sees. Perimenopause can last anywhere from a few months to ten years, with an average of around four.

Menopause: a date you can only see in hindsight

Menopause itself is defined as twelve consecutive months with no period. Because you can only count those twelve months once they have passed, menopause is always a backward-looking diagnosis. The average age in the UK is fifty-one. Reaching it under forty-five is called early menopause, and under forty it is called premature ovarian insufficiency, which needs a different and more proactive approach. If that may apply to you, we assess it individually.

Post-menopause: the long phase after

Once you are past that twelve-month mark you are post-menopausal, and you remain so for the rest of your life. Oestrogen settles at a low level. Hot flushes ease for many women within a few years, although for a significant minority they persist for a decade or more. Other changes are slower and quieter: vaginal and urinary symptoms tend to appear later and, unlike flushes, get worse with time rather than better if untreated, because they are driven by the ongoing lack of oestrogen in those tissues.

Do you need a test to know?

For most women over forty-five, the answer is no. The diagnosis is made from your symptoms and your menstrual pattern, and a blood test for the hormone FSH is not required and can even mislead, because levels swing so much in perimenopause. Tests have a clearer role under the age of forty-five, or where the picture is unusual, and a doctor will arrange them when they will actually change what happens next.

What is normal, and when to look closer

Irregular periods, hot flushes and sweats, sleep and mood changes, and the gradual onset of vaginal dryness are all expected parts of the transition. Some things are not, and deserve prompt attention: bleeding after sex, bleeding between periods that is new, very heavy bleeding, or any bleeding at all once you are post-menopausal. These are usually not sinister, but they need checking rather than assuming.

Why it varies so much from woman to woman

Two women the same age can have completely different experiences, and that is normal. Genetics play a large part: the age your mother reached menopause is a rough guide to your own. Some things bring it forward, including smoking, which advances menopause by a year or two on average. Surgery matters too: removing both ovaries causes an immediate, surgical menopause whatever your age, and a hysterectomy that leaves the ovaries in place can still bring menopause on a little earlier.

Symptom severity varies just as widely. Around a quarter of women have severe symptoms, around a quarter have few, and most sit somewhere in between. How much your symptoms affect you, rather than how typical they look on paper, is what should drive whether and how you treat them.

Where this leaves you

Understanding which stage you are in matters because it shapes what helps. Perimenopausal symptoms can be treated even while you are still bleeding, and you still need contraception until the menopause is confirmed. If your symptoms are affecting your daily life, you do not have to wait until your periods have stopped to do something about them.

Ready to start?

If you want to move from reading to acting, the next step is a short assessment with a doctor on the GMC GP Register. It takes about ten minutes and tells you whether HRT is right for you.

Begin your assessment at this link. Online or in person at Westfield London.