Perimenopause periods: every way they change, and what is normal

The usual sequence

The transition follows a recognisable order, even though any individual month can break it.

Cycles usually shorten first. A 28-day cycle becoming a 25-day cycle is the earliest change most women notice, and it happens because the first half of the cycle speeds up as the ovaries respond less efficiently to FSH.

Then cycles become erratic — some short, some long, some skipped. A gap of 60 days or more marks late perimenopause. Then they stop, and twelve months later the transition is over.

The whole sequence takes around four years on average and can run to ten.

Why bleeding gets heavier

This is counterintuitive: hormones are declining, so why is there more blood?

The answer is the imbalance rather than the level. A cycle without ovulation produces estrogen but no progesterone. Estrogen builds the womb lining; progesterone matures it and organises an orderly shedding. Without progesterone, the lining keeps building and is eventually shed in an unstructured way, which means heavier, longer, more clotted bleeding.

So heavy perimenopausal periods are usually a sign of too little progesterone, not too much estrogen in any absolute sense.

What counts as expected

Ordinary perimenopausal variation covers a wide range:

• Cycles anywhere from about 21 to 60 days, varying month to month
• Periods lasting two days one month and seven the next
• Bleeding noticeably heavier or lighter than it used to be
• Skipped months, then a return to bleeding
• New or worse period pain
• Premenstrual symptoms arriving earlier or hitting harder

What is not just perimenopause

These need assessing rather than absorbing into the general chaos:

• Bleeding between periods, consistently
• Bleeding after sex
• Any bleeding at all after twelve months without a period
• Flooding through protection in an hour, or passing clots larger than a 10p coin or a quarter
• Periods consistently closer together than 21 days
• Bleeding lasting longer than seven days, repeatedly

When to see someone

Heavy bleeding deserves an appointment on its own terms, not as a footnote to a menopause discussion. It is a very common cause of iron deficiency, which then produces fatigue, breathlessness and palpitations that get attributed to hormones. A full blood count and ferritin are worth asking for.

Keep a simple record of dates and heaviness for a few months. It establishes your stage, and it is the thing most often missing at the appointment.