Perimenopause is the stretch of time before your final period when the hormones governing your cycle stop behaving predictably. It is not a steady decline. It is a period of instability, which is precisely why it is so hard to recognise from the inside.
The word people get wrong
Menopause is a single day: the date of your final period. You only know it has happened in hindsight, once 12 months have passed without another.
Everything before that day is perimenopause. Everything after it is postmenopause.
This matters because almost everything people describe as "going through menopause" is actually perimenopause — and perimenopause is the phase where symptoms are typically most unpredictable, because levels are swinging rather than settling.
| Stage | What it means | Typical age in Australia |
|---|---|---|
| Perimenopause | Cycles become irregular; levels fluctuate | Commonly 40s, sometimes late 30s |
| Menopause | The final period — identified 12 months later | Average 51 to 52 |
| Postmenopause | Everything after that date | 52 onward |
Source: health.gov.au, Jean Hailes.
What is actually happening
Through your reproductive years, the ovaries release an egg roughly monthly, and the hormones that drive that cycle rise and fall in a fairly regular pattern.
In perimenopause the ovaries become less responsive. The body compensates by signalling harder, which can push levels higher than usual in some cycles and much lower in others. Some months an egg is released, some months it is not.
So the defining feature is not that levels drop. It is that they stop being predictable. That is why:
- Symptoms come and go, sometimes disappearing for months
- Periods may be heavier before they become lighter
- Two women the same age can have completely different experiences
- A blood test on a single day often does not tell you much
That last point surprises people. Because levels swing, a test taken on one day can look entirely normal while you are firmly in perimenopause. For most women over 45, the diagnosis is made from the pattern of symptoms and cycle changes, not from bloods.
How long it lasts
Commonly four to ten years. Some women pass through in under two. Some experience symptoms for a decade or more.
There is no way to predict your own course in advance, though going through it earlier than average, or having a mother who did, is loosely associated with an earlier transition.
When it starts earlier than expected
If periods stop before 45 it is called early menopause. Before 40 it is called premature ovarian insufficiency, and it affects about 1 in 100 women.
Both warrant prompt medical attention rather than waiting — the management considerations are different from menopause at the average age, particularly around long-term bone and cardiovascular health.
Contraception still matters
Ovulation in perimenopause becomes unpredictable, not absent. Pregnancy is still possible, and unplanned pregnancy in the mid-forties is more common than most people assume.
The general guidance is to continue contraception until 12 months after your final period if you are over 50, or 24 months if you are under 50. Which method suits you is worth discussing with your doctor, since some methods also affect bleeding patterns and can make the transition harder to track.
What to do with this
If the pattern sounds familiar, the useful next step is not to self-diagnose but to arrive at an appointment with a clear record.
Our symptom summary tool builds one you can print or copy. Then preparing for your appointment covers what a good consultation looks like and what to ask.