What Is Menopause? Understanding the Three Stages — and Why So Many Women Miss the First One

You have been told for years that menopause is something that happens when your periods stop. You have probably also heard that it happens "around 50." Neither of those things is wrong, exactly. But is it the full picture? Not quite — and the gap between the two is where a lot of women miss what is happening in their own bodies.

So let us start with what menopause actually is. Not just the textbook version. The version that actually helps you make sense of what is happening in your body.

Menopause is three stages, not one

When women say "I am going through menopause," they usually mean one of three different stages. The treatments and the conversations differ for each, so the language matters.

Perimenopause is the years when your hormones begin fluctuating. Oestrogen, progesterone, and testosterone all change — but not smoothly. Levels swing. This is why symptoms come in waves. Perimenopause typically begins in the mid-to-late 40s and can last anywhere from two to twelve years. The median age for the first signs is 47 — which means half of women experience signs earlier (Australasian Menopause Society 2024; SWAN study).

Menopause itself is a scientific definition. It is the day when twelve consecutive months have passed without a natural period. The complication is that this definition is only useful if you are still having periods to count. If you have had a hysterectomy, or a Mirena IUD that stops your bleeding, that marker disappears — and the diagnosis depends on your symptoms and your age rather than on a date. The average age in Australia is 51. The normal range is 45 to 55.

Post-menopause is every day after that. For most women, this is the longest stage of their adult life.

What is actually happening in your body

You are born with all the follicles — the structures in your ovary that house eggs — you will ever have. As you move through your 40s, those follicles become fewer and less able to do their job.

By the time you reach perimenopause, the remaining follicles are fewer, and less able to do their job. What that means in practice is that they are less likely to mature into the kind of follicle that releases an egg. This is also why fertility declines through your late 30s and 40s, even before periods change. The follicles are still there. They are just not as responsive as they once were.

Your brain notices. It releases more follicle-stimulating hormone (FSH) to try to keep the system going. Sometimes the ovary responds with a surge of oestrogen. Sometimes it does not respond at all. This is why your hormones swing in perimenopause rather than gently decline. It is also why you can feel fine for a month and then wake at 3am every night for the next three (Casperson & Smith 2025).

What you may not have been told

For many women, periods do not change until they are well into perimenopause, or even near the end of it. A regular cycle does not rule out perimenopause — and a doctor who tells you "your periods are fine, you cannot be perimenopausal" is working from an outdated definition. (Newson 2023.)

How perimenopause is actually diagnosed

For women over 45, the current guidance from leading menopause societies — the Australasian Menopause Society, NICE in the UK, and the International Menopause Society — is clear: perimenopause is a clinical diagnosis based on symptoms and age, not a blood test.

What that means in practice is that a doctor should be able to make this diagnosis by listening to you. By hearing your symptoms, your history, and your age. Your symptoms and your age are the standard, not your blood test.

Hormone levels in perimenopause fluctuate constantly. You may get a "normal" blood test result — but that does not necessarily tell us the true picture. A snapshot taken on a single day cannot capture a moving target.

Why this matters for you

If you have been told you are "too young" because you are in your 40s, that is a misunderstanding of statistics. Forty-seven is the median age for the first signs of perimenopause. Half of women experience it earlier.

If you have been told "your bloods are normal, you are fine," that may also be a misunderstanding of how perimenopause works. Normal bloods on a Tuesday do not rule out fluctuating hormones.

If your periods are still regular but you feel like a different person — exhausted, irritable, foggy, sore — your symptoms are still real. Regular periods do not rule out perimenopause either.

Three takeaways

1. Menopause is three stages — perimenopause, menopause, and post-menopause. The treatments and conversations differ for each.

2. The average age of natural menopause is 51, but symptoms commonly begin in the mid-to-late 40s. Earlier is normal too.

3. For women over 45, perimenopause is a clinical diagnosis. Your symptoms and your age are enough.

This is not your body failing you. It is your body changing — and asking for a different kind of support.

Start by noticing patterns. Track your symptoms over the next two to three months — sleep, mood, cycle, joints, energy, libido, brain. Two to three months captures the cyclical pattern of perimenopausal hormones. Most women are surprised to learn there are over 40 documented symptoms of perimenopause — not just hot flushes. Sleep, mood, joints, brain, energy, libido, skin, bladder. Write them all down.

Want a full list of the symptoms?

Download the free Menopause Hub Symptom Checklist:

This information is educational only and does not constitute personal medical advice. Always consult a qualified health professional about your individual circumstances.

© 2026 Menopause Hub | Anna Pattison | menopausehub.com.au

References

Australasian Menopause Society (AMS). menopause.org.au (2024).

NICE. Menopause: diagnosis and management. Guideline NG23 (updated 2024).

International Menopause Society (IMS). Climacteric (2024 update).

Casperson K, Smith J. Perimenopause is Real. You Are Not Broken podcast, episode 324 (2025).

Newson L. The Definitive Guide to the Perimenopause. 2023.

SWAN — Study of Women's Health Across the Nation. nia.nih.gov/swan-study (accessed 2026).