Perimenopause: First Signs, Stages and How It Is Diagnosed

Perimenopause usually starts in the mid-forties with periods that come more or less often and bleeding that gets heavier or lighter, alongside hot flushes, broken sleep and mood changes; over 45, NICE says it is identified on those symptoms alone, without blood tests, and under 40 the rules are different.^{1, 2} What the menopause is, and what comes after it, is on the Wellgard menopause guide.

What are the first signs of perimenopause?

The NHS symptoms page (reviewed 19 May 2026) puts it plainly: "One of the first signs of perimenopause is usually a change to your periods." They "may happen more often or less often, and bleeding may get heavier or lighter."¹ The NHS names these, each covered on its own page:

• Changes to your periods, the sign most women notice first.¹
• Hot flushes and night sweats: in the SWAN cohort, women whose frequent flushes began before or early in the transition had the longest course, a median of more than 11.8 years.³ Hot flushes that have recently started are also one of NICE's two markers of perimenopause.²
• Sleep problems: in 3,045 women followed over seven annual assessments, difficulty falling and staying asleep rose through the transition.⁴ See perimenopause sleep problems.
• Mood changes, poor memory and brain fog, which the NHS says "may feel worse if you have sleep problems and feel very tired".¹ See why you are so tired in perimenopause; the one perimenopause trial of memory and mood is on creatine in perimenopause and menopause.
• Weight gain, "often around the stomach and upper body".¹
• Vaginal dryness, burning, irritation or itching, and more UTIs or UTI-like symptoms: vaginal dryness at any age.
• Other symptoms on the NHS list: palpitations, loss of bone density, incontinence, "headaches and migraines that are worse than usual", muscle aches and joint pains, hair thinning, dry and itchy skin, reduced sex drive, and sensitive teeth or painful gums.¹

The NHS notes that women from a Black ethnic background are "more likely to have hot flushes that are severe and continue longer".¹

What are the stages of perimenopause, and how long does it last?

Clinicians stage the transition by bleeding pattern. The 2011 STRAW+10 workshop set out simplified bleeding criteria for an early and a late menopausal transition and recommended that they apply "regardless of women's age, ethnicity, body size, or lifestyle characteristics".⁵ In practice that is the NHS description: periods that come more or less often, then stop; the transition ends at the final period, and the menopause is dated 12 months after it.^{1, 2}

How long it lasts varies. The NHS says: "Symptoms usually last for 7 to 9 years, sometimes longer", and that they change over that time, flushes giving way to low mood and anxiety for some women.¹ In SWAN, the median duration of frequent flushes was 7.4 years, and they persisted a median of 4.5 years after the final period.³

How is perimenopause diagnosed in the UK?

On symptoms, for most women. NICE guideline NG23 (last updated 15 April 2026) tells clinicians to identify, "without laboratory tests", in otherwise healthy people aged 45 or over: perimenopause, where there are "vasomotor symptoms that have recently started and any changes in their menstrual cycle"; and menopause, where there has been no period for at least 12 months and no hormonal contraception is being used.² NICE adds that "it can be difficult to identify menopause in people who are taking hormonal treatments", and that people from some ethnic minority backgrounds and with some lifelong conditions "may experience menopause at a younger age".²

The tests NICE says not to use. At 45 or over: anti-Müllerian hormone, inhibin A, inhibin B, oestradiol, antral follicle count and ovarian volume.² An FSH blood test is not used in anyone on combined oestrogen and progestogen contraception or high-dose progestogen, and is considered to confirm menopause "only" at 40 to 45 with symptoms including a change in cycle, or under 40.² That is why a home FSH kit or a saliva hormone panel cannot answer the question: over 45 the hormones they measure are not part of the diagnosis, and under 40 NICE requires two laboratory samples, never one result.²

Perimenopause at 39, and "too young". The NHS early menopause page (reviewed 11 March 2025) says: "Early menopause is when you stop having regular periods before the age of 45", and "Premature menopause is if this happens before the age of 40"; under 45 "a GP may sometimes do blood tests".⁶ Under 40 the diagnosis is premature ovarian insufficiency, which NICE makes on menopause-associated symptoms, including no or infrequent periods, plus raised FSH "on 2 blood samples taken 4 to 6 weeks apart", never "on the basis of a single blood test", with referral to a specialist if there is doubt.² The 2024 international guideline estimates that 3.5% of women are affected.⁷ The NHS says replacing the missing hormones before 45 matters because of "a higher chance of getting problems with your bones and heart".⁶

Can I still get pregnant, and when can I stop contraception?

Yes, you can. The NHS: "It's possible to get pregnant during perimenopause." Contraception is still needed "for 2 years after your final period, if you're aged 40 to 49", and "for 1 year after your final period, if you're 50 or over".¹ The NHS adds that "the combined pill is not recommended if you're aged 50 or over", and that a GP may recommend a progestogen-only method.¹

Hormonal contraception also blurs the picture. The progestogen-only pill, hormonal coil, implant and injection can make periods irregular or stop them, and the combined pill produces monthly bleeds for as long as you take it, so the usual "12 months without a period" cannot be read.¹ On a GLP-1 medicine the oral pill carries its own absorption rule (the pill and HRT on a GLP-1 medicine), and weight loss itself can change cycles (GLP-1 medicines and your periods).

What changes in periods are normal, and which need a GP?

Lighter, heavier or irregular periods are the NHS pattern for perimenopause.¹ Three changes need a GP: bleeding that is heavier or more frequent than before, bleeding after sex, and any bleeding a year or more after your last period. The NHS wording is "you're bleeding more, not less, than before", and for postmenopausal bleeding to see a GP "even if it's only happened once", or if it is only spotting or pink or brown discharge.¹ About one in ten women with bleeding after the menopause is found to have womb cancer, and about nine in ten womb cancers announce themselves that way.⁸ The NHS postmenopausal bleeding page (reviewed 24 September 2026) says "Postmenopausal bleeding is not usually serious" and "You should not have to wait more than 2 weeks to see a specialist".⁹ Heavier periods in the forties also raise the question of iron, answered on heavy periods and iron.

What does the NHS offer in perimenopause?

The NHS treatment page (reviewed 19 May 2026) says: "talk to a doctor, nurse or pharmacist about HRT and other options available".¹⁰ NICE says: "Offer HRT to people with vasomotor symptoms associated with menopause", and to consider menopause-specific cognitive behavioural therapy "as an option for vasomotor symptoms", alongside HRT or for people who cannot or prefer not to take it.² NICE also says to offer vaginal oestrogen for vaginal and urinary symptoms, and that "serious adverse effects are very rare".² In perimenopause the NHS notes that HRT "can make your periods more regular", and that irregular bleeding or spotting on it "should settle within 6 months".¹ What type and whether it suits you is decided with your GP. The non-hormonal medicines and therapies, as the NHS and NICE describe them, have their own page.

When should I see a GP?

The NHS says to contact a GP if you think you have perimenopause or menopause symptoms and "want to know what your options are", if you have palpitations, if your bleeding pattern has changed and you are bleeding more, or if you have any bleeding 12 months or more after your last period, adding that "Early advice can help reduce the effects of menopause and perimenopause".¹ If the change is in your mood, the NHS early menopause page notes that "You can get NHS talking therapies without seeing a GP first".⁶

Frequently asked questions

What age does perimenopause start?

The NHS says the menopause "usually affects women between the ages of 45 and 55", so the changing cycles before it typically begin in the mid-forties.⁶ NICE notes it may come younger in some ethnic minority groups and with some lifelong conditions.²

Do I need a blood test to confirm perimenopause?

Over 45, no: NICE identifies it on symptoms "without laboratory tests". At 40 to 45 a GP may consider an FSH test; under 40, two FSH samples 4 to 6 weeks apart are required, and no FSH test is read on combined hormonal contraception.²

How do I know if I am in perimenopause or menopause?

Perimenopause is changing cycles with symptoms; menopause is 12 months without a period while not on hormonal contraception.^{1, 2}

Can perimenopause start at 35?

Periods stopping before 40 is premature ovarian insufficiency, estimated at 3.5% of women; NICE diagnoses it on symptoms plus two FSH results, and the NHS early menopause page describes the route.^{2, 6, 7}

Can I take the pill in perimenopause?

That is a GP decision. The NHS says the combined pill is not recommended at 50 or over, and NICE says an FSH test cannot be used while you take it, so the pill can mask where you are.^{1, 2}

Sources

1. NHS. Symptoms of menopause and perimenopause. Reviewed 19 May 2026. nhs.uk.
2. NICE. Menopause: identification and management (NG23), recommendations 1.3.1 to 1.3.6, 1.5.1, 1.5.2, 1.5.5, 1.5.6 and 1.7.1 to 1.7.5. Published 12 November 2015, last updated 15 April 2026. nice.org.uk.
3. Avis NE, et al. Duration of menopausal vasomotor symptoms over the menopause transition. JAMA Internal Medicine, 2015. PubMed 25686030.
4. Kravitz HM, et al. Sleep disturbance during the menopausal transition in a multi-ethnic community sample of women. Sleep, 2008. PubMed 18652093.
5. Harlow SD, et al. Executive summary of the Stages of Reproductive Aging Workshop + 10: addressing the unfinished agenda of staging reproductive aging. Journal of Clinical Endocrinology and Metabolism, 2012. PubMed 22344196.
6. NHS. Early or premature menopause. Reviewed 11 March 2025. nhs.uk.
7. Panay N, et al. Evidence-based guideline: premature ovarian insufficiency. Human Reproduction Open, 2024. PubMed 39660328.
8. Clarke MA, et al. Association of endometrial cancer risk with postmenopausal bleeding in women: a systematic review and meta-analysis. JAMA Internal Medicine, 2018. PubMed 30083701.
9. NHS. Postmenopausal bleeding. Reviewed 24 September 2026. nhs.uk.
10. NHS. Treatment for menopause and perimenopause. Reviewed 19 May 2026. nhs.uk.