What is happening in your body
Your ovaries release eggs less reliably. Oestrogen swings between high and low, sometimes higher than it was in your thirties. Progesterone falls first, because it is only made after an egg is released.
High oestrogen phases can bring breast tenderness, heavy bleeding and irritability. Low phases bring hot flushes, poor sleep and low mood. The swings explain why the same woman can feel fine one month and unwell the next.
Early signs
Cycles shorten, often to 21 to 25 days, before they lengthen. Bleeding gets heavier or lasts longer. Premenstrual symptoms get worse. Night sweats appear in the days before a period. Sleep breaks up. Anxiety arrives for the first time.
Later, periods space out. Once you go 60 days or more between periods, your final period is usually within one to three years.
How it is diagnosed
If you are over 45 and have symptoms, diagnosis rests on your symptoms and your cycle. Blood tests are usually not needed, because a single result can look normal on the day.
If you are under 45, your practitioner may check follicle stimulating hormone, thyroid function, iron and pregnancy to rule out other causes.
Treatment in perimenopause
You do not have to wait for your periods to stop. Hormone therapy can be started now. A hormonal intrauterine device controls heavy bleeding and doubles as the progestogen part of hormone therapy.
If you cannot or prefer not to take hormones, treatments for hot flushes, sleep and mood still work. Iron supplements help if heavy bleeding has left you low in iron.
Contraception still matters
Pregnancy is possible until you have gone twelve months without a period over 50, or two years under 50. Keep using contraception until then, or until your practitioner confirms it is safe to stop.
See a practitioner if
- Bleeding soaks a pad or tampon every hour for several hours
- A period lasts more than seven days
- You bleed after sex or between periods
- You bleed again after twelve months without a period
Common questions
Can I be in perimenopause at 40?
Yes. Most women start in their mid forties, but symptoms can begin earlier. If your periods stop before 40, that is a different condition and needs assessment. See the premature menopause page.
Why are my blood tests normal?
Hormones swing from day to day. A test on a high oestrogen day looks normal. That is why guidelines advise against relying on blood tests in women over 45.
How do I track it?
Use a calendar or app. Record bleeding days and your top five symptoms, each scored from 0 to 3. Three months of records gives your practitioner a clear picture.
- National Institute for Health and Care Excellence, Menopause: identification and management, NG23, updated 2024
- Australasian Menopause Society, perimenopause information sheet
- Stages of Reproductive Aging Workshop, STRAW plus 10 staging system, 2012
This page is education, not medical advice. Talk to your doctor or menopause practitioner about your own care. In an emergency, call your local emergency number.