What is perimenopause? A plain definition
Perimenopause is the time leading up to your last period; the word means "around menopause." [1] During it your ovaries make different, unpredictable amounts of estrogen and progesterone, you may not ovulate every month, your periods become irregular, and symptoms such as hot flashes can begin. [1]
Perimenopause, menopause, postmenopause: the three terms
Perimenopause, also called the menopausal transition, is the stretch of years before the final period. [1][2] Menopause is the point when periods have stopped permanently and you can no longer get pregnant; you have reached it only after a full year with no bleeding, including spotting. [1] Everything after is postmenopause, when the ovaries make very low levels of estrogen and progesterone. [1] People often say "menopause" for the whole thing, but the National Institute on Aging notes that true menopause can't be confirmed until one year after the final period. [2] It also says plainly that menopause is not a disease or disorder; it is a normal part of aging for women. [2]
What is happening in the body?
Hormone levels do not fall in a smooth line. The Office on Women's Health says that as the body transitions, hormone levels may change randomly, causing symptoms unexpectedly, and that the ovaries make different amounts of estrogen and progesterone than usual, eventually leading to very low levels. [1] Irregular periods happen because you may not ovulate every month. [1] The Menopause Society attributes the changing periods to the ovaries' erratic hormone production and less frequent release of an egg. [3] This randomness is why a single hormone blood test is a poor guide to where you are. [1]
When does it start and how long does it last?
Perimenopause usually starts in a woman's mid-to-late 40s and lasts about four years for most women, with a range of two to eight. [1] The National Institute on Aging says most women begin the transition between 45 and 55. [2] ACOG notes that estrogen output begins to fluctuate in the 30s and 40s. [4] The average age of menopause in the United States is 52 by the government's count and 51 by ACOG's. [1][4] We cover the timeline in detail in when perimenopause starts and how long it lasts.
What does perimenopause feel like?
It varies enormously. Some women have no or very mild symptoms; for others they begin suddenly and are very noticeable. [1] Many women report no physical change during perimenopause except irregular periods. [5] When symptoms do come, the most commonly reported are hot flashes and night sweats, which up to 80% of women experience at some point in the transition; vaginal dryness, sleep disturbances and mood changes are the other common ones. [3][5] The National Institute on Aging's list adds joint and muscle discomfort, pain during sex, forgetfulness and difficulty concentrating. [2] Our article on the signs of perimenopause goes through each, including what is normal and what is not. For most women, most symptoms improve after menopause, even without treatment. [5]
How is perimenopause diagnosed?
Mainly from the story, not a lab. The Office on Women's Health says it can be hard even for your provider to tell, and that the useful signals are your symptoms and tracking your periods; providers don't usually recommend a hormone test unless there is a medical reason, such as periods stopping before 40, because levels swing unpredictably. [1] The National Institute on Aging says your doctor may ask about your age, symptoms and family history to judge whether the transition is the likely cause. [2] In the UK, the NICE guideline is explicit: identify perimenopause without laboratory tests in otherwise healthy women aged 45 or over who have recently started hot flashes and have changes in their cycle, and do not use anti-Müllerian hormone, estradiol or related tests for this purpose at that age. [6] That is UK guidance, but it reflects the same biology.
Can perimenopause be treated?
The symptoms can, if they bother you. The National Institute on Aging says many women find they do not need treatment, and that for those who want it the options may include lifestyle changes, non-hormone medications and hormones, chosen by discussing your symptoms, medical and family history and preferences with your doctor. [2] One practical point: you can still get pregnant during perimenopause, so if you do not want to, keep using birth control until a full year after your last period. [1]
When to talk to your clinician
ACOG says that although changes in bleeding are normal in perimenopause, you should still report them, because abnormal bleeding can be a sign of a problem. [4] Any bleeding after you have gone twelve months without a period is not normal and should be seen as soon as possible. [1] And if you feel moodier, more anxious or low in a way that is affecting your life, the Office on Women's Health says to see your provider; mood changes are common, but depression is a separate illness that needs its own care. [1]
If you are in crisis, call or text 988 (US), any time, free and confidential.
Sources
- Office on Women's Health, Menopause basics. Page last updated April 2, 2026. Retrieved 2026-10-17.
- National Institute on Aging, What Is Menopause? Content reviewed October 16, 2024. Retrieved 2026-10-17.
- The Menopause Society, Perimenopause (patient education). Retrieved 2026-10-17.
- American College of Obstetricians and Gynecologists, The Menopause Years. Last reviewed December 2025. Retrieved 2026-10-17.
- The Menopause Society, Symptoms (patient education). Retrieved 2026-10-17.
- NICE (UK), Menopause: identification and management, NG23, recommendations 1.3.1 and 1.3.4. Last updated April 15, 2026. Retrieved 2026-10-17. UK guidance.
Every statement above was checked against the linked source on the date shown. This article is education, not individual medical advice. Related: Signs of perimenopause · Perimenopause symptoms, in full.