Last checked September 2026 against 14 sources · Editorial policy
What age does perimenopause start?
Perimenopause usually starts in your 40s. In the Massachusetts Women's Health Study, the median age at onset was 47.5, and it lasted nearly 4 years before the final period. Menopause itself usually happens between 45 and 55, at a median age of 51.4 in SWAN. It can start earlier: menopause before 45 is called early menopause, and before 40 premature ovarian insufficiency. Smoking brings it forward.
Most women start perimenopause in their 40s; some notice changes in their late 30s. What sets your timing, the first signs, and how it differs from menopause.
Perimenopause age: expectation vs reality
What people often expect
“Menopause is something that happens in your 50s”
What the evidence shows
The final period usually comes around 51, but the transition leading to it starts years earlier. In the Massachusetts study, perimenopause began at a median of 47.5, and SWAN found that the earlier it began, the longer it lasted: a median of 8.57 years for women who started earliest. So the changes many women notice in their mid-40s are often perimenopause, not stress or aging.
What age does perimenopause start, and why it varies
The average age perimenopause starts
In the Massachusetts Women's Health Study, which followed 2,570 women aged 45 to 55, the median age at the start of perimenopause was 47.5 and the median age at natural menopause was 51.3. SWAN, a study of 14,620 US women aged 40 to 55, found a median age at menopause of 51.4. The UK average is 51. So for most women, perimenopause starts somewhere in the mid to late 40s.
Why some women start perimenopause earlier
Smoking is the strongest known factor: in the Massachusetts study, current smokers reached menopause 1.8 years earlier than non-smokers, and SWAN found smoking linked with an earlier start and a shorter transition. SWAN also linked lower education, being separated, widowed or divorced, not being employed and a history of heart disease with earlier menopause. A family history of early menopause, starting periods early and being underweight raise the chance too.
Why some women start perimenopause later
In SWAN, having had children, having used the pill in the past, and Japanese ethnicity were linked with a later menopause, and a higher body mass index was linked with a later start of the transition. These are associations from large studies, not levers you can pull: there's no proven way to delay perimenopause, though not smoking avoids bringing it forward.
How early can perimenopause start?
Menopause before 45 is early menopause, and before 40 premature ovarian insufficiency. A meta-analysis estimated early menopause at 12.2% of women and premature ovarian insufficiency at 3.7%. It can happen naturally or after surgery to remove the ovaries, chemotherapy, radiotherapy or some hormone treatments. Replacing hormones matters in these women, because early menopause raises the risk of osteoporosis and heart disease.
Learn more →Starting early means a longer transition
In SWAN, the age at which the transition began largely decided how long it lasted. Women in the youngest quarter at onset had a median transition of 8.57 years, while women in the oldest quarter had 4.37 years. African American women also had longer transitions than white women. If your changes start in your early 40s, expect a longer run.
Signs perimenopause has started, at any age
The first sign is usually a change in periods: they come more or less often, or get heavier or lighter. STRAW+10 defines the early transition as cycle lengths that differ by 7 days or more, again and again. Hot flashes, sleep problems, mood swings and brain fog often come alongside. If you're 45 or over, NICE says a doctor can diagnose perimenopause from these symptoms without blood tests.
Average age of perimenopause by the numbers
From the studies on this page
of women reach menopause early, before 45, in a global meta-analysis
12.2%
have premature ovarian insufficiency, menopause before 40
3.7%
47.5
51.4
These are medians: half of women start earlier and half later. Your own timing depends on genes, smoking, health and chance.
What to do if you think perimenopause has started
Track your cycle to spot the start of perimenopause
First stepLog the first day of each period, how heavy it is and any symptoms like hot flashes or poor sleep. A difference of 7 days or more between cycles that keeps happening marks the early transition. A few months of records tell you and your doctor far more than a single blood test.
Related guide →Get checked if symptoms start before 45
If this is the causeUnder 45, a doctor may do blood tests. Between 40 and 45 an FSH test can help, and under 40, premature ovarian insufficiency is diagnosed with raised FSH on 2 samples taken 4 to 6 weeks apart. Early diagnosis matters because hormone replacement protects bones and heart.
Related guide →Treat symptoms at any age
Strong evidenceYou don't have to wait for your periods to stop. HRT can be started in perimenopause and cuts hot flashes by about 75%. If you also need contraception, the combined pill until 50 can control cycles and ease hot flashes. Non-hormonal medicines and CBT are options too.
Related guide →Stop smoking
First stepSmoking is linked with an earlier start of perimenopause and earlier menopause, and the NHS notes it can make menopause symptoms worse. Stopping protects your bones and heart as well. If you smoke, ask your doctor or pharmacist about support to quit; it is one of the few things that affects when menopause arrives.
When your age means you should see a doctor
Periods stopping or symptoms starting before 40
See a doctor. This may be premature ovarian insufficiency, which needs blood tests and usually hormone treatment.
More →Symptoms starting between 40 and 45
See a doctor. Early menopause raises the risk of osteoporosis and heart disease, and treatment helps.
Urgent: Bleeding 12 months or more after your last period
Always get it checked. You should see a specialist within 2 weeks.
More →
Perimenopause age: questions women ask
What age does perimenopause start?
Usually in your 40s. The median age at onset was 47.5 in the Massachusetts Women's Health Study. It can start earlier, especially in smokers, and menopause before 45 is called early menopause. The first sign is usually a change in your periods, often with hot flashes or sleep problems.
What is the average age of perimenopause?
Perimenopause starts at a median of about 47.5 and lasts about 4 years, with the final period at a median of about 51. The UK average age of menopause is 51. The full range is wide: most women reach menopause between 45 and 55.
How early can perimenopause start?
It can start in your late 30s or early 40s. Menopause before 45 is early menopause, affecting about 12.2% of women in one meta-analysis, and before 40 it's premature ovarian insufficiency, about 3.7%. Symptoms before 45 are worth a doctor's check.
What is the perimenopause age range?
Most women go through perimenopause somewhere between their early 40s and mid 50s, since menopause usually happens between 45 and 55. The transition lasts about 4 years on average and longer when it starts early.
When do women usually start perimenopause?
Usually in the mid to late 40s. Smoking, a family history of early menopause, starting periods early and being underweight make an earlier start more likely. Having had children and past pill use are linked with a later menopause.
What is the earliest age for perimenopause?
There's no fixed earliest age. Premature ovarian insufficiency can happen before 40, and occasionally much younger, naturally or after surgery, chemotherapy or radiotherapy. Under 40, it's diagnosed with blood tests, and hormone replacement is usually recommended.
Related →Does your mother's age at menopause predict yours?
It can help. The NHS says you have a higher chance of early menopause if it runs in your family. Other factors, especially smoking, also shift timing, so it's a guide rather than a rule.
Can you tell what age perimenopause will start from a blood test?
Not reliably. Hormone levels swing too much in the lead-up to menopause, and NICE advises against using FSH tests to diagnose perimenopause over 45. Your cycle pattern and symptoms are better guides. A 2-minute symptom check and a few months of cycle tracking give a clearer picture.
Is 45 too young for perimenopause?
No. Menopause usually happens between 45 and 55, so perimenopause at 45 is normal. The median age at onset in one large study was 47.5, so many women start a little before or after that. Only menopause itself before 45 is called early. If you are 45 or over, a doctor can diagnose perimenopause from your symptoms without blood tests.
Can perimenopause start at 40?
Yes. At 40, it is earlier than average but not unusual, and menopause between 40 and 45 counts as early menopause, which affects about 12.2% of women. See a doctor if your periods change or symptoms start in your early 40s: an FSH blood test may help confirm it, and treatment protects your bones and heart.
How old are you when perimenopause begins?
Most women are in their 40s when perimenopause begins, with a median age of 47.5 in the Massachusetts Women’s Health Study. The age group most affected is roughly the early 40s to mid 50s, since menopause usually happens between 45 and 55. A minority start earlier, and menopause before 45 is called early menopause.
Sources
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- Gold EB, Bromberger J, Crawford S, et al. Factors associated with age at natural menopause in a multiethnic sample of midlife women. Am J Epidemiol. 2001;153(9):865-74.
- NHS. What are menopause and perimenopause?
- NHS. Early or premature menopause.
- Paramsothy P, Harlow SD, Nan B, et al. Duration of the menopausal transition is longer in women with young age at onset: the multiethnic Study of Women's Health Across the Nation. Menopause. 2017;24(2):142-149.
- Women's Health Concern (British Menopause Society). Contraception for women over the age of 40. Fact sheet, 2025.
- Golezar S, Ramezani Tehrani F, Khazaei S, et al. The global prevalence of primary ovarian insufficiency and early menopause: a meta-analysis. Climacteric. 2019;22(4):403-411.
- NHS. Symptoms of menopause and perimenopause.
- Harlow SD, Gass M, Hall JE, et al. Executive summary of the Stages of Reproductive Aging Workshop + 10. J Clin Endocrinol Metab. 2012;97(4):1159-1168.
- NICE. Menopause: identification and management (NG23). Updated 2024.
- NHS. Irregular periods.
- Crandall CJ, Mehta JM, Manson JE. Management of Menopausal Symptoms: A Review. JAMA. 2023;329(5):405-420.
- NHS. Things you can do to help menopause and perimenopause symptoms.
- NHS. Postmenopausal bleeding.
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