Irregular periods in perimenopause

Shorter, longer, heavier, lighter, skipped. Here's what's normal — and the specific changes that are worth a call.

5 minute read

Here's the plain-English version. One of the most disorienting things about perimenopause is that your period — something you've planned around for decades — becomes unpredictable. That's not a sign something's wrong. It's the single most reliable sign that your body is transitioning.

What's actually happening

In perimenopause, some months you ovulate and some you don't. A cycle without ovulation is called an anovulatory cycle. When ovulation doesn't happen, you don't make much progesterone — but you're still making estrogen. The lining of your uterus keeps building. Eventually it sheds, and when it does, it can be heavier and longer than what you're used to.

What's normal

• Cycles getting shorter (every 21–24 days) — common in early perimenopause
• Cycles getting longer or skipped — common in mid/late perimenopause
• Heavier flow on some cycles and lighter on others
• PMS that suddenly feels different or worse
• Spotting a day or two before a period starts

When to actually call a doctor

• Bleeding so heavy you soak through a pad or tampon every hour for more than 2 hours.
• Bleeding for more than 7 days in a row.
• Bleeding between periods — not just spotting, actual bleeding.
• Any bleeding at all once you've gone 12 months without a period.
• Cycles shorter than 21 days consistently.

These aren't automatically a problem, but they warrant a check to rule out fibroids, polyps, or something that needs treatment.

How long does the unpredictable part last?

For most women, the changes span 4–8 years. Periods get weirder, then they skip, then they're gone. You're officially in menopause on the day that marks 12 straight months with no period.