For most women the first real sign of perimenopause is not a hot flush. It is the cycle changing — often years earlier, and often not recognised for what it is.
What changes, and in what order
Roughly, though individual experience varies enormously:
Cycles shorten first. A reliable 28-day cycle becomes 25, then 24. Periods seem to arrive constantly. This is frequently the earliest sign and is rarely connected to perimenopause, because women expect periods to become less frequent.
Variability increases. A cycle varying by seven days or more between consecutive periods is a recognised marker of early perimenopause — 26 days, then 33, then 27.
Flow changes. Often heavier, sometimes with clots, sometimes lasting longer.
Cycles lengthen and gaps appear. Later in the transition, periods start being skipped. A gap of 60 days or more marks late perimenopause.
They stop. Confirmed only in hindsight, 12 months later.
The whole sequence commonly takes four to ten years and is rarely this tidy. Periods that vanish for four months and return are normal in this context.
Why bleeding often gets heavier
This is the part that surprises people, and the mechanism is worth understanding.
In a typical cycle an egg is released, and the hormone produced afterwards stabilises the uterine lining and brings on a period of predictable size.
In perimenopause many cycles occur without an egg being released. Without that second hormone, the lining continues to build under the influence of the first, which is itself fluctuating and sometimes unusually high. When it eventually sheds, there is more to shed.
Hence: heavier periods, sometimes after a longer gap, sometimes with clots.
When heavy is too heavy
"Heavy" is subjective and women consistently under-report, largely because you have no comparison — your normal is all you have ever known.
Some practical markers. Bleeding is worth raising if you:
- Soak through a pad or tampon every hour for several hours
- Need double protection
- Regularly need to change protection overnight
- Pass clots larger than a fifty-cent piece
- Bleed for more than eight days
- Plan your work, travel or clothes around your period
- Have symptoms of low iron — fatigue, breathlessness on stairs, palpitations,
pale skin, hair loss
That last point matters more than any other. Heavy periods are the most common cause of iron deficiency in women, and iron deficiency produces exhaustion, poor concentration and low mood — which then get attributed to perimenopause generally. It is a simple blood test and a treatable cause of feeling terrible.
What is expected and what needs checking
| Pattern | Interpretation |
|---|---|
| Cycles shortening to 24 to 26 days | Expected in early perimenopause |
| Variation of a week or more between cycles | Recognised marker of the transition |
| Skipped months, then a return | Expected in later perimenopause |
| Somewhat heavier periods | Common, but check iron |
| Bleeding between periods | Needs assessment |
| Bleeding after sex | Needs assessment |
| Cycles closer than 21 days | Needs assessment |
| Bleeding more than 8 days | Needs assessment |
| Any bleeding 12 months after your last period | Needs prompt assessment |
The bottom four are not about alarm; they are about the fact that other conditions — fibroids, polyps, thickening of the lining, and occasionally something more serious — become more common in this age group and are best found early.
Tracking
A record is worth more than a description here, and it takes seconds a day.
Note the first day of each period, how many days it lasts, and roughly how heavy. Any period tracking app works, as does a paper diary. Three months of this transforms a conversation with a doctor from "they have been all over the place" into something specific.
If your cycle has become erratic, this is also the most reliable way to notice a gap approaching 12 months.
Contraception
Worth repeating because the assumption catches people out: irregular cycles still contain ovulation, just unpredictably. Pregnancy remains possible.
General guidance is to continue contraception until 12 months after your final period if you are over 50, or 24 months if under 50. Which method suits you is worth discussing, since some also affect bleeding.
What to discuss with a doctor
Bring your cycle record. Ask about iron — specifically ferritin — if bleeding has been heavy. Ask what is causing the pattern rather than assuming perimenopause explains all of it, particularly if anything in the "needs assessment" list above applies.
Related
What perimenopause is explains the underlying hormonal picture. If heavy bleeding has left you exhausted, fatigue covers the overlap.