Knowledge base

When is your cycle irregular?

Almost nobody has the same cycle every month. The question is not whether it varies, but how much.

Variation is normal

In research across more than 600,000 cycles, 87 percent of women had a cycle between 23 and 35 days, and more than half saw differences of five days or more between consecutive cycles. Two cycles of 26 and 33 days in a row are not a deviation.

Ovulation is not fixed on day 14

In that same research, ovulation in a 28-day cycle was spread across ten days, with day 15 the most common. An app that assumes day 14 is using an average that almost nobody is.

When it is worth discussing

If your period stays away for more than three months without pregnancy, if you lose far more blood than you are used to, or if your pattern changes suddenly, call your doctor, even if you feel fine otherwise.

Sources

Soumpasis, Grace, Johnson, Human Reproduction Open (2020), Real-life insights on menstrual cycles and ovulation using big data
NHS, Heavy periods

General information, not medical advice. In doubt, or things are not going well? Call your doctor.

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