What is perimenopause?
Perimenopause is the transition that leads up to your last period. It can last for years, and it is driven by hormones that fluctuate rather than simply fall, which is why the symptoms are so wide-ranging and come and go. These guides explain what to expect, what is normal, and when to speak to your doctor, all grounded in published research.
When it starts, and how it feels
Perimenopause usually begins in the mid-forties, about four years before your final period, though it can start earlier and last longer (Journal of Clinical Endocrinology & Metabolism, 2021; UpToDate, 2025). During this time the ovaries wind down unevenly, so oestrogen and progesterone swing up and down and periods start to change in timing and heaviness.
In women aged 45 and over, perimenopause is recognised from symptoms and cycle changes alone, without a blood test (NICE guideline NG23, 2024). The experience is different for everyone, which is why understanding your own pattern matters more than any single symptom.
Guides to perimenopause
Perimenopause symptoms
The common symptoms, grouped by cluster, and what is normal.
Read the guide →
The stages of perimenopause
The four stages, the ages they arrive, and how to tell where you are.
Read the guide →
HRT in perimenopause
What it is, the main types, and what the guidance says. Information, not advice.
Read the guide →
How long does perimenopause last?
The honest answer, and how to tell it is ending.
Read the guide →
Perimenopause vs menopause
The three stages, explained simply.
Read the guide →
Perimenopause and sleep
Why sleep breaks, and what the data shows.
Read the guide →
Perimenopause brain fog
Real, measurable, and usually temporary.
Read the guide →
Perimenopause and mood
Is it perimenopause, stress, or both?
Read the guide →
Weight gain around the middle
Why fat shifts, independent of the scales.
Read the guide →
Can a wearable track perimenopause?
An honest answer about what the data can show.
Read the guide →How anna fits
anna reads the patterns already sitting in your wearable data and gives you a clear, daily explanation of what your body is doing and why, drawing on a library of over 1,000 clinician-reviewed rules. No symptom diary, nothing to log. Translation, not tracking.
See what your body is telling you
anna is on iOS across the UK and Europe. Seven days free, then choose monthly or annual.
