How regular is a woman’s period?

Illustration of a girl writing in a diary on a red background - Libresse

Recently started your period? Don’t worry if they aren’t regular yet – this isn’t a sign that there’s a problem.

In fact, it often takes a while to settle into a pattern. And once you do, that pattern will be unique to you.

The menstrual cycle, which is counted from the first day of your period to the day before your next period begins, isn’t the same for every woman. An average cycle is 28 days, but it can be as short as 21 days or as long as 35 days. Bleeding can also last anywhere between two and seven days.

Your normal menstrual flow should establish itself after the first few months of your cycle, but it may take up to a year. Go and see your doctor if you are having irregular periods or ‘spotting’ between periods – also known as ‘abnormal bleeding’. Reasons for missing a period can include stress, overdoing sporty activities, sudden weight loss, taking the pill or being pregnant.

Did you know?

28 days
average duration of the menstrual cycle
3-8 days
average duration of a period
30-40 ml
average amount of blood in a period

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At any one time, a quarter of women of reproductive age are menstruating. And yet, there is a still a great deal of confusion about how periods affect women’s lives.
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Once your periods have started, knowing what’s happening in your body – and why – can make a huge difference to how you feel about them.
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