Why the diagnosis is made looking backwards
The menopause is diagnosed once 12 consecutive months have passed without a period. Once those 12 months are complete, the date of the last period is taken, retrospectively, as the moment of menopause. It is therefore a point that can only be identified after it has happened.
The process occurs as the reserve of eggs (follicles) in the ovaries runs out. As that pool declines, levels of oestrogen, progesterone and testosterone first fluctuate and then fall permanently.
The stages
- Perimenopause (the transition): the period in which hormones begin to fluctuate, the pattern of periods changes and the first symptoms may appear. Periods may become heavier, lighter, more frequent or less frequent. It lasts on average 4 to 8 years. Progesterone is usually the first hormone to fall; because it has a calming, sleep-promoting effect, sleep can suffer as it declines.
- Menopause: the point defined by 12 consecutive months without a period.
- Postmenopause: the time after the menopause.
At what age?
Natural menopause usually happens between the ages of 45 and 55, with an average of about 51. There are ethnic and geographical differences in the age of onset. It is estimated that more than 80% of women have reached the menopause by the age of 54.
Early menopause and ovarian insufficiency
- Under 40: this is called premature ovarian insufficiency (POI). It affects about 1 in 100 women under 40, 1 in 1,000 under 30 and 1 in 10,000 under 20.
- Between 40 and 45, periods stopping permanently is described as early menopause.
Menopause that is not natural
- Surgical menopause: both ovaries removed at operation.
- Medical menopause: ovarian function permanently lost because of radiotherapy, chemotherapy or certain treatments.
Anyone who is going to enter the menopause because of surgery or medical treatment should be told about the effects in detail before it happens. It is important that people who go through early, surgical or medical menopause have access to continuing support.
Symptoms
Not everyone who reaches the menopause has symptoms — about one in four has none at all. Of those who do, 80–90% have symptoms, and 25% of them describe those symptoms as severe and disruptive to daily life.
The most common are hot flushes and night sweats (vasomotor symptoms); they occur in 70–80% of women. Others include:
- Disturbed sleep and insomnia
- Low energy and fatigue
- Low mood and anxiety
- Reduced sexual desire
- Difficulty with memory and concentration — often described as "brain fog"
- Joint pains, headaches, palpitations
- Vaginal dryness and urinary symptoms
When hormone levels fluctuate the body has to adapt. Because hormone receptors are found throughout the body, the symptoms can look unrelated to one another and may not at first be connected with the menopause.
How long do they last?
Symptoms last on average more than 7 years. It is estimated that more than a third of women have long-lasting symptoms that can continue for years. During perimenopause symptoms may come and go; some ease while others become more noticeable.
Long-term effects on health
When the ovaries stop producing oestrogen, the fall in hormone levels can also affect long-term health.
- Bone health: the female skeleton depends on oestrogen to keep its strength and resistance to fracture. Falling oestrogen increases the risk of osteoporosis (thinning of the bones). A hot flush or vaginal dryness is noticed; osteoporosis, by contrast, has no clear symptom — the first sign may be a fracture.
- Heart health: the lack of oestrogen after the menopause has been shown to increase the risk of heart disease in women.
How is it diagnosed?
The diagnosis is made by taking a careful history: in people over 45 what matters is assessing symptoms together with the change in the pattern of periods.
Over the age of 45 a hormone blood test (FSH) is not useful for diagnosis, because the FSH level fluctuates from month to month and may not give an accurate picture. If ovarian insufficiency is suspected under 40, FSH is measured and repeated if the result is unclear. Between 40 and 45, FSH may help where early menopause is suspected; symptoms and the change in periods are assessed alongside it. A single test may not give the diagnosis.
Frequently Asked Questions
How do I know I have reached the menopause?
If 12 consecutive months have passed since your periods stopped, you are considered to have reached the menopause; the date of your last period is taken retrospectively as the moment of menopause. The stage before those 12 months are complete, when periods become irregular and symptoms can begin, is called perimenopause.
Do I need a blood test to diagnose the menopause?
Usually not, if you are over 45 — an FSH test is not useful for diagnosis in that age group, because the level fluctuates from month to month. The diagnosis is made from your symptoms and the change in your periods. Under 40, FSH is measured if ovarian insufficiency is suspected; between 40 and 45 it may help. A single test may not give the diagnosis.
Does everyone get hot flushes?
No. About one in four women has no symptoms at all. Hot flushes and night sweats are the most common symptoms and occur in 70–80% of women. Of those who do have symptoms, 25% describe them as severe and disruptive to daily life.
How long will my symptoms last?
On average more than 7 years. More than a third of women have long-lasting symptoms that can continue for years. During perimenopause symptoms may come and go; some ease while others become more noticeable.
Can insomnia and forgetfulness be part of the menopause?
Yes. Because hormone receptors are found throughout the body, symptoms can look unrelated to each other. Disturbed sleep, fatigue, anxiety, difficulty with memory and concentration ("brain fog"), joint pains, palpitations and headaches are all recognised. In perimenopause the first hormone to fall is usually progesterone; because it has a calming, sleep-promoting effect, sleep can suffer as it declines.
Can the menopause happen before 40?
Yes. Menopause under the age of 40 is called premature ovarian insufficiency (POI) and affects about 1 in 100 women under 40 (1 in 1,000 under 30, 1 in 10,000 under 20). Periods stopping permanently between 40 and 45 is described as early menopause.
What happens if my ovaries are removed?
Removing both ovaries at operation is called surgical menopause; loss of ovarian function through radiotherapy or chemotherapy is called medical menopause. In these situations the menopause begins abruptly. You should be told about the effects in detail before the operation or treatment, and have access to continuing support afterwards.
Does the menopause do any long-term harm?
Falling oestrogen has long-term effects in two areas: an increased risk of osteoporosis and of heart disease. Osteoporosis has no clear symptom — the first sign may be a fracture. The menopause is therefore a good time to review lifestyle and health screening.
Sources
- British Menopause Society (BMS) — Tool for Clinicians: "What is the menopause?". Reviewed January 2026. Definition, diagnostic approach, frequency and duration of symptoms, long-term health effects.
- STRAW+10 staging criteria — defining the stages of the menopause by menstrual cycle length.
The information on this page is based on the national and international guidelines listed above. The page is reviewed whenever those guidelines are updated.
Practice and Contact Details
The information on this page is general. Please speak to your doctor about your own situation.
- DoctorOp. Dr. Murat Alpay — Specialist in Obstetrics and Gynaecology
- AddressOp. Dr. Murat Alpay Practice, Tekelioğlu Cd. No:51 B Kat:2, Filo Apt., 07160 Muratpaşa / Antalya
- Telephone0505 351 77 88
- HoursMonday – Saturday 09:00 – 18:00 · Closed on Sunday