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What is irregular bleeding?

On average, a menstrual cycle lasts between 24 and 38 days, but what happens if yours isn’t regular or predictable?

For many, periods don’t follow a predictable pattern. More than 3 in 4 women and girls have experienced irregular periods and 1 in 7 experience this every cycle.

Despite being common, irregular periods could be a sign of an underlying gynaecological condition, so it’s important not to dismiss this as “normal”.

What should you be looking for?

What is an irregular period?

You may have been taught that your period should come every 28 days. But it can be slightly longer or shorter than this.

Your periods are irregular if:

  • the gap between your periods is less than 21 days or more than 35 days
  • the number of days in between each of your periods is different and keeps changing
  • the amount of menstrual blood changes from one period to the next

If you are experiencing irregular periods that impact your life, make an appointment to see your GP. You should also visit your GP if you have any spotting in between periods or after sex, as this could be a sign of something more serious.

What causes irregular periods?

Things that can cause irregular periods include:

  • puberty, when you start your periods
  • the start of menopause (usually between the ages of 45 and 55)
  • pregnancy – a missed period is often an early sign of pregnancy
  • hormonal contraception like the progestogen-only pill, contraceptive injection and intrauterine system (IUS – a hormonal coil)
  • Stress and anxiety
  • Lifestyle factors such as losing or gaining a lot of weight or exercising too much
  • Medical conditions such as an underactive thyroid gland

Some gynaecological conditions can also cause irregular periods, including:

Very rarely, irregular periods could be a sign of womb or cervical cancer.

Visiting a doctor for irregular periods

Your first step is to see your GP – find out how to prepare for your appointment here.

It is helpful to keep track of your periods ahead of your appointment and details like how far apart they are, how long they last, how heavy they are, and what impact they have on your life.

Your doctor may want to carry out a vaginal exam, especially if you have other symptoms such as severe period pain, heavy bleeding, bleeding or pain during or after sex, or bleeding between periods. Your GP may also do a blood test to check if you’re anaemic; if you are having frequent periods it could lead to anaemia.

They may refer you onto a gynaecologist if they suspect an underlying cause.

Treatments for irregular periods

Treatment isn’t always needed for irregular periods and will depend on if there’s an underlying cause.

Your doctor will work with you to find the best options:

For example:

  • Are you thinking about starting a family?
  • What might happen if you don’t have treatment?
  • Are there any side-effects to treatments?
  • Finding the answers to these questions can help you make the right decision for you.

Can I get pregnant with irregular periods?

It can be more challenging to get pregnant if you have irregular periods as you may not be releasing an egg regularly.

If you want to get pregnant, it is recommended that you have sex every 2-3 days without contraception throughout your cycle.

If you are still struggling, you should speak to your doctor who may recommend hormone medicine or fertility treatment.


Our “periods information hub is here to help educate and empower women, girls and people who menstruate. Get more information and support here.

If you have any symptoms or concerns, always speak to your doctor. 

Our research on periods and menstrual health

As a women’s health charity, part of what we do is fund research to save and change the lives of women, girls and babies.