Cycle

What Causes Irregular Periods?

2026-06-26 · 2:04 · Menstrual Cycle

The short answer

What causes irregular periods? First, what counts as irregular? It's when your cycle length varies a lot from month to month, or you genuinely can't predict when your period will come. A few common things drive it, some harmless, some worth checking. Let me run through them.

In this video

"Irregular" = cycles that vary a lot or are unpredictable

Most common: PCOS and thyroid issues

Two of the most common medical causes are PCOS, polycystic ovary syndrome, and thyroid problems. Both affect the hormones that drive ovulation, and when ovulation is irregular, your periods are too. These are very worth identifying, because they're manageable once you know.

Lifestyle: stress, big weight changes, intense exercise

Lifestyle plays a big role too. High stress, significant weight gain or loss, intense exercise, and poor sleep can all delay or skip ovulation. Your cycle is sensitive, it's often one of the first things to shift when your body is under strain.

Life stages: puberty, perimenopause, after stopping the pill

Some irregularity is just a life stage. Cycles are often irregular in the first years after your periods start, again in perimenopause, while breastfeeding, and for a little while after stopping hormonal birth control. In these cases, it's usually your body adjusting.

See a doctor if: sudden change, very irregular, or trying to conceive

When should you get it checked? If your periods suddenly become irregular, if they're so unpredictable you can't track them, if you go many months without one, or if irregular cycles are making it hard to conceive. A doctor can check simple things like hormones and thyroid to find the cause.

PinkyBloom, link in description. Educational only, not medical advice.

So, to recap: irregular periods usually come back to irregular ovulation, driven by things like PCOS or thyroid issues, by stress, weight, or intense exercise, or by life stages like puberty and perimenopause. See a doctor if it changes suddenly, you can't predict it, or it's affecting trying to conceive. Tracking with PinkyBloom helps you and your doctor spot the pattern, link's in the description. This video is for general education and isn't a substitute for professional medical advice. Take care, and I'll see you in the next one.

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