Perimenopause does not start when your periods stop

There is a widespread belief that menopause is something that happens at around 50, announces itself with hot flushes, and starts when your periods stop.

The last part is the wrong way round. Menopause is defined retrospectively, as the point 12 months after your final period. Everything leading up to it is perimenopause, and that stretch can begin years earlier and run for a long time.

How long is a long time

Perimenopause commonly lasts around 4 to 8 years, and for some women considerably longer. It can begin in the mid to late 30s. Most women are in it well before anyone uses the word.

Which means it is entirely possible to be deep in perimenopausal change while your periods are still arriving more or less on schedule. Regular periods do not rule it out.

What is actually happening

The picture people carry around is of hormones gently declining down a slope. The reality is messier and it explains a great deal.

In the earlier part of perimenopause, oestrogen does not simply fall. It fluctuates, sometimes reaching higher peaks than in your 30s, then dropping steeply. Progesterone tends to decline earlier and more steadily, because cycles where no egg is released become more common, and it is ovulation that produces progesterone.

So you can get a stretch where oestrogen is erratically high and progesterone is low. That combination accounts for a lot of what women describe: heavier or more painful periods, sore breasts, worse premenstrual weeks, poor sleep, and a shorter fuse.

Later on, the fluctuation settles into decline, and the more familiar symptoms tend to come forward.

The symptoms that get attributed to something else

Hot flushes and night sweats are well known. These are the ones that often are not connected to hormones at all.

• Sleep that breaks at 3am. Falling asleep is fine. Staying asleep is not.
• Anxiety that feels new, often in women who have never been anxious, and often worst in the days before a period.
• Word finding and concentration. The sense of being slightly behind your own brain.
• Joint aches and stiffness, particularly in the morning.
• Cycle changes. Shorter gaps, heavier bleeding, or skipped months.
• Recurrent urinary symptoms and vaginal dryness, which tend to persist and progress rather than pass.
• Palpitations, migraine changes, dry eyes, itchy skin, and a general sense of the dial being turned up on everything.

Taken one at a time, each of these has an obvious alternative explanation. Taken together, in a woman in her 40s, the pattern is often the diagnosis.

Why a blood test often does not settle it

This is the question we are asked most. Can I not just have my hormones tested?

You can, and sometimes it is useful, but it is less decisive than people expect. During perimenopause hormone levels swing substantially from day to day and cycle to cycle. A single measurement captures one moment in a moving system, and a result taken on a good day can look entirely reassuring while a result taken a fortnight later looks quite different.

This is why national guidance advises diagnosing perimenopause and menopause in women over 45 on symptoms and cycle pattern rather than on hormone blood tests. Testing has a clearer role in younger women, where periods have stopped early, or where the picture is genuinely unclear.

Where testing does earn its place is in ruling other things in or out. Thyroid problems, low ferritin and low vitamin D produce overlapping symptoms and are common, treatable and easy to miss. Being tired, foggy and low is not automatically hormonal.

What is worth doing

• Track it. Two or three cycles of notes on bleeding, sleep, mood and symptoms is more useful than any single blood test, and it makes an appointment far more productive.
• Ask for the overlapping things to be checked, particularly thyroid function, ferritin and vitamin D.
• Take the timeline seriously. This is not a fortnight of turbulence. Decisions worth making are the ones that hold up over years.
• Do not wait for it to become undeniable. The window where things are subtle is the easiest one in which to act.

Where this gets looked at properly

Initial Consultation

History, pattern and what to do next

At-home Blood Test

For the overlapping things worth ruling out

Restored Programme

When this needs following over months

The point

Perimenopause is not the finish line, it is the long approach to it. Knowing that you are in it changes what you make of your own symptoms, and it changes what you ask for.

You do not have to wait until your periods stop to take this seriously.