Perimenopause
Also called the menopause transition, premenopause
Reviewed August 2026 against NHS, NIH and WHO references.
In short
Perimenopause is the transition into menopause, when hormone levels start to swing and periods become irregular. It often begins in the 40s and can last several years. Hot flashes, broken sleep, mood changes and heavier or lighter periods are common while the ovaries wind down.
What is happening in your body
Perimenopause means 'around menopause'. The ovaries do not switch off in one step. They wind down over years, and while they do, estrogen and progesterone rise and fall in a way that gets less predictable. Those swings, not a steady decline, are what drive most of the symptoms.
Because the hormone that is falling touches so much of the body, the signs show up in many places at once: the temperature system (hot flashes), sleep, mood, memory, joints, skin and the vaginal and urinary tissues. This is why perimenopause can feel like several unrelated problems arriving together.
When it starts and how long it lasts
Perimenopause commonly starts in the mid-40s, though it can begin earlier. It lasts until menopause itself, the point of twelve months with no period, and often runs for four to eight years. The one change most women notice first is that the timing or the flow of their periods shifts.
How it is recognized
For most women over 45, perimenopause is recognized from symptoms and the pattern of periods, not from a blood test. Hormone levels swing so much day to day that a single reading rarely settles anything. A test is more useful when symptoms start young or the picture is unclear.
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Related terms
Sources
This definition is for general information only and is not medical advice. Menopause care depends on your individual health history. Please talk to a qualified clinician about what is right for you.