Perimenopause vs menopause: the difference that changes treatment

The definitions

Perimenopause is the transition leading up to your final period. Hormone levels fluctuate. Periods become irregular. Most symptoms happen here. It typically lasts four to eight years.

Menopause is a single point in time: twelve months after your last period. It can only be identified in hindsight.

Postmenopause is everything after that day.

So a woman with irregular periods and hot flushes is perimenopausal, not menopausal, even though everyone including her will say "I'm going through the menopause".

The difference that matters clinically

In perimenopause, symptoms are driven by fluctuation. Oestrogen swings high and low, sometimes within a single cycle, and progesterone drops away as ovulation becomes irregular. That is why symptoms come and go, why a good week means nothing, and why a single blood test is close to useless.

In postmenopause, symptoms are driven by sustained low levels. Things are stable, just stable at a low level.

That difference shows up in treatment. In perimenopause you may still be ovulating some months, so a treatment regime often needs to work with a cycle that still exists. After menopause, there is no cycle to work around.

Can you still get pregnant?

In perimenopause, yes. Ovulation is unpredictable, not absent. Pregnancy is less likely but entirely possible, and contraception is still needed.

General guidance is contraception until 55, or for two years after your last period if you are under 50, and one year if you are over 50. HRT is not contraception, which is one of the most consequential misunderstandings in this area.

After menopause, no.

Symptoms that behave differently

Most vasomotor symptoms, the flushes and sweats, are common in both and often peak around the final period.

Vaginal and urinary symptoms behave differently. They tend to arrive later, and unlike flushes they do not settle by themselves, because they are caused by ongoing lack of oestrogen in the tissue rather than by fluctuation. Left alone they usually get worse.

Bone loss accelerates around and after menopause, silently.

How to tell which you are in

If you are still having periods at all, however irregular, you are perimenopausal.

If it has been twelve months since your last period, you are postmenopausal.

If you have had a hysterectomy but kept your ovaries, or you have a hormonal coil, you may not have periods to go by, and symptoms become the guide. That is a situation worth having assessed rather than guessed.

And the rule that applies to both

Any bleeding after twelve months without periods is not part of either picture and needs a doctor, usually within weeks.