Irregular periods in perimenopause: what’s normal, and what isn’t
Closer together, further apart, heavier, lighter, gone for two months and back again. Here’s how to read what your cycle is doing.
The short answer
Irregular periods are often the first sign of perimenopause. Early on, cycles usually vary by seven days or more from month to month; later, you may go 60 days or more between periods. Flow can get heavier or lighter. Get checked if bleeding gets much heavier, happens between periods or after sex, or returns after twelve months without a period.
Why periods become irregular in perimenopause
In perimenopause, ovulation becomes less predictable. Estrogen doesn’t simply decline in a straight line — it swings higher and lower from cycle to cycle — while progesterone, which is made after ovulation, tends to fall first. Your cycle is the most direct readout of that, which is why a change in periods is so often the first thing women notice.
What irregular looks like, stage by stage
Researchers use the STRAW+10 criteria to describe the transition by what your cycle is doing:
| Stage | What your cycle does |
|---|---|
| Early transition | A persistent difference of 7 days or more in the length of consecutive cycles — for example 24 days, then 33, then 26. |
| Late transition | Going 60 days or more without a period. |
| Menopause | Twelve consecutive months without a period. |
It’s common to move back and forth: a skipped month, then three regular ones. That’s the fluctuation, not a sign something has gone wrong.
Common changes you might notice
- Shorter cycles — periods arriving closer together, often early in the transition.
- Longer gaps and skipped months — more typical later on.
- Heavier or lighter flow — the NHS lists both. Some women have a run of heavy periods; others notice lighter, shorter ones.
- Longer periods or more spotting before a period starts.
- A period “coming back” after a few months away.
Heavy periods matter beyond the inconvenience: repeated heavy bleeding can lower iron, which is one reason perimenopause fatigue is worth taking seriously.
When irregular bleeding should be checked
Most cycle changes in perimenopause are expected. These are the ones to get looked at rather than watched:
- bleeding that becomes much heavier — the NHS specifically advises contacting a GP if bleeding gets heavier rather than lighter
- bleeding between periods or after sex
- any bleeding after twelve months without a period — the NHS says this needs checking “even if it’s only happened once”
- periods that leave you dizzy, breathless or exhausted
Usually there’s a simple explanation, but these are the patterns where “it’s probably perimenopause” shouldn’t be the end of the conversation.
How to track it without it taking over your life
You don’t need an elaborate app. Track three things for three cycles:
- the date your period starts
- flow in one word (light, normal, heavy)
- how you felt in one word
Three cycles of that is more useful at an appointment than a single hormone test taken on a random day — because in perimenopause, hormone levels swing from day to day.
If you use hormonal contraception, a hormonal IUD, or have had surgery that affects your periods, your cycle may not tell you much. In that case your other symptoms — sleep, hot flashes, mood, focus — are the clearer signal.
Can you still get pregnant?
Yes. Irregular isn’t the same as infertile. Cleveland Clinic is clear that pregnancy is still possible during perimenopause as long as you’re having periods, so keep using contraception if you don’t want to conceive — and take a test if a period is unusually late.
Common questions
Are irregular periods the first sign of perimenopause?
Often, yes — a change in periods is one of the most common first signs. But sleep, mood or focus changes can come first, especially if contraception masks your cycle.
Is it normal to skip a period for two months in perimenopause?
Going 60 days or more without a period is a recognised marker of the late menopause transition. Take a pregnancy test if there's any chance, and see a clinician if bleeding returns much heavier or you're unsure.
Why are my periods closer together in my 40s?
Shorter cycles are common early in perimenopause because ovulation becomes less predictable and hormone levels fluctuate. If they're very frequent or very heavy, get them checked.
When should I worry about bleeding in perimenopause?
Get checked for bleeding that becomes much heavier, bleeding between periods or after sex, bleeding that leaves you dizzy or exhausted, or any bleeding after twelve months without a period.
Sources
- Harlow et al. — Executive summary of STRAW+10 (Menopause, 2012)
- NHS — Symptoms of menopause and perimenopause
- Cleveland Clinic — Perimenopause
- NICE guideline NG23 — Menopause: identification and management
This guide is educational. It doesn't diagnose or treat anything and isn't a substitute for personalized medical advice.