Perimenopause Is More Than Hot Flushes: What Actually Changes in Midlife
Last month I was in Sydney for the Australasian Menopause Society Congress. I came home with pages of notes, a very full brain, and one idea that turned up in almost every session.
Menopause is more than hot flushes.
It is about supporting women through a transition from one stage of life to the next. It means more than mood swings, hot flushes and night sweats. Every woman will experience this transition differently, and it starts at different times for everyone.
There is also a significant gap in care, and it often begins with not recognising perimenopause in the first place.
Most of us grew up with one picture of menopause: a woman in her fifties, fanning herself through a hot flush. So when you are 44, still getting periods, and suddenly anxious, exhausted and losing words mid-sentence, menopause is the last thing on your mind.
Often it is the last thing on anyone else's mind too.
This is the first of four pieces I am writing for World Menopause Month. I want to start where most women start: "I don't feel like myself anymore, but I can't explain what's wrong."
What perimenopause actually means
Perimenopause is the lead-up to your final period. Menopause itself is a single point in time: 12 months after that last period. Everything after it is postmenopause.
The lead-up is not short. Hormone levels can fluctuate for four to five years, and longer for some women. In research presented at the congress, the median age for entering the early stage was 47. The late stage, when periods begin to skip, was 49. Those are midpoints, so plenty of women start earlier.
Here is the part that surprises people. Oestrogen does not decline quietly through these years. It swings. High one month, low the next. That is why symptoms come and go, and why you can feel fine in March and unrecognisable in May.
Hot flushes get the attention. They are often not the main event.
It can start before your periods change
The staging system clinicians use relies mostly on your cycle. Under it, perimenopause begins when the length of your cycle varies by seven days or more. Hot flushes are not part of the criteria at all.
The Australian Women's Midlife Years (AMY) study, published in 2025, challenged that. Researchers looked at 5,509 Australian women aged 40 to 69. Women with regular cycles, whose periods had become much heavier or lighter and who also had hot flushes or night sweats, had symptoms just as severe as women officially in early perimenopause.
Their conclusion: perimenopause likely begins before cycles start to vary. Regular periods do not rule it out.
One of the teaching cases at the congress was a 47-year-old with a mostly regular cycle, heavier periods, new night sweats, worsening mood and brain fog. She had been told she could not be perimenopausal because her cycle had not changed enough. That story is common, and the evidence no longer supports it.
The symptoms nobody warned you about
One survey of women attending a specialist menopause clinic in the UK recorded 84 different symptoms. The most common were fatigue, memory problems and irritability, each reported by more than nine in ten women. Hot flushes came in 47th. These were women already seeking specialist care, so the numbers run high, but the pattern is worth noticing.
What that can look like in real life:
Waking at 2 or 3am and not getting back to sleep
Anxiety that seems to arrive from nowhere
Irritability or rage that feels out of character
Losing words, losing your train of thought, forgetting why you walked into the room
Fatigue that rest does not fix
Aching joints and muscles
Periods that are heavier, lighter or closer together
Changes in libido, vaginal dryness or bladder symptoms
Many women arrive having been told, "Your hormones are normal."
A woman I saw recently is very good at her job. She had started losing words in meetings and making mistakes she had never made before. She was embarrassed, and she had begun to doubt herself.
Brain fog in perimenopause is real. Researchers describe it as trouble with memory, attention, word finding and holding a train of thought. It is also usually subtle. Most women still perform within the normal range on formal testing, and for many it settles after menopause. As one speaker put it, brain fog is not a slippery slope to dementia.
That does not make it trivial. For some women it affects their work and their confidence. Which is why the question I always ask next is: "How are your symptoms affecting you?"
Why a normal blood test does not settle it
In perimenopause, hormone levels shift from week to week, sometimes day to day. A blood test captures one moment. You can have a completely normal result on Tuesday and still be well into perimenopause.
For women over 45 with typical symptoms, the diagnosis is made by listening: your symptoms, your cycle and your history. In one congress case discussion, the first clinical decision for a 47-year-old with symptoms was to not order hormone blood tests.
There are times testing matters. If you are under 45 and your periods are changing, and especially if you are under 40, hormone tests are part of working out what is going on. Around 4 in 100 women have ovaries that slow down before 40. That needs proper investigation, not reassurance.
When it is not perimenopause, or not only perimenopause
Here is the other side. Not every symptom after 40 is hormonal.
Fatigue, low mood, poor sleep and brain fog are common in perimenopause. They are also common with thyroid problems, low iron, depression and other conditions. One of the international speakers made the point that women are at higher risk of autoimmune conditions in midlife, and that vague symptoms can be the first sign of something else.
So a good assessment keeps both possibilities open. Depending on your story, that may mean checking iron, thyroid, blood sugar and cholesterol. Not to diagnose perimenopause, but to make sure nothing else is being missed.
Some things should always be checked rather than put down to your age:
Very heavy periods, flooding or large clots
Bleeding between periods or after sex
Any bleeding once you have gone 12 months without a period
Periods becoming infrequent or stopping before 40
"If something's not right, stop being dismissed."
If your history is complicated
The standard staging system depends on your periods. That means it does not work well if you have PCOS, have had a hysterectomy or endometrial ablation, or use hormonal contraception that changes your bleeding.
Endometriosis and fibroids add their own layers, because heavy or painful periods may have more than one cause.
If that is you, generic menopause advice probably has not fit. You are not harder to help. Your assessment simply needs to lean on your symptoms and history rather than your cycle.
Where to start
You do not need a diagnosis to start paying attention. This week:
Track your symptoms alongside your cycle for a few weeks. Note flow as well as timing.
Write down how each symptom affects your life: sleep, work, relationships, exercise.
Gather your history: periods, pregnancies, and any family history of heart disease, osteoporosis, blood clots or breast cancer.
Take it to your GP or women's health clinician and ask directly: could this be perimenopause, and what else should we rule out?
There may be an explanation for what you are feeling. And if there is, there are options.
Next week: what menopause means for your heart, bones, muscles and brain.
Know a woman who keeps saying "I just don't feel like myself"? Send her this.
This article is general health information and does not replace individual medical advice. Please speak with your own health practitioner about your circumstances.
Sources
Islam RM, Bond M, Ghalebeigi A, et al. Prevalence and severity of symptoms across the menopause transition: cross-sectional findings from the Australian Women's Midlife Years (AMY) Study. Lancet Diabetes Endocrinol 2025;13:765.
Santoro N. New Insights Into Perimenopause. Australasian Menopause Society Congress, 2026.
Elliott J. Decision making in a menopause consultation. AMS Menopause Essentials Update, Sydney, September 2026.
Lappin J. Optimizing Brain Health During the Menopause Transition. Australasian Menopause Society Congress, 2026.
Uppal T. Midlife and Menopausal Bleeding: When Should We Worry? Australasian Menopause Society Congress, 2026.
Panay N, Anderson R, Bennie A, et al. Evidence-based guideline: premature ovarian insufficiency. Climacteric 2024;27:510.
Davis SR, Taylor S, Hemachandra C, et al. The 2023 Practitioner's Toolkit for Managing Menopause. Climacteric 2023;26(6):517.
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