Irregular Periods

Your period can be an important indicator of your overall health. However it’s sometimes hard to know when you should visit a doctor about your period. Here we talk about what an ‘irregular period’ is, what affects your menstrual cycle and when and how to speak to your doctor about it. 

What is an ‘irregular period’?

When the term irregular period is used what is actually being referred to is the menstrual cycle – the time from the first day of a woman’s period to the day before her next period. A regular period is a good indicator that ovulation is happening. Ovulation (the release of an egg from an ovary) is an essential part of getting pregnant. 

A period is regular if the time between your first day of bleeding and the day before the next time you are bleeding is greater than 21 days and less than 35 days and month to month the number of days doesn’t change a lot. 

A menstrual cycle is thought to be irregular if:

  • A cycle is less than 21 days or more than 35 days
  • You have less than 8 cycles per year 
  • You have a cycle longer than 90 days

In the first years after you start menstruating your periods tend to be more irregular. Usually after about 3 years they tend to become more consistent. As such there are different criteria depending on the number of years since your first period:

  • In the first year after your first period – it’s normal to have irregular periods
  • Between 1 – 3 years after your first period – a cycle less than 21 days or greater than 45 days is irregular

What causes irregular periods?

There are a number of causes of irregular periods including lifestyle changes, diet changes and any medication you may be taking. Often it isn’t anything to worry about but it’s worth discussing with your doctor to make sure everything is OK.

Some possible causes of irregular periods are:

  • PCOS – a hormonal condition that is common in women of reproductive age
  • Extreme weight loss or weight gain
  • Excessive exercise or stress
  • Some types of hormonal contraception – such as the contraceptive pill or intrauterine system (IUS) or stopping contraception (usually only within the first 3 months)
  • Certain medical conditions – such as a problem with the thyroid
  • The start of the menopause (usually between the ages of 45 and 55)
  • Early signs of pregnancy – a pregnancy test will rule this out

When to see your GP

It can feel a bit uncomfortable to visit your GP about your period but it’s important to speak with an expert if you think there’s something wrong. You can read more about how to speak to your GP here

Generally it’s worth seeing a GP if:

  • your periods suddenly become irregular and you’re under 45
  • you have periods more often than every 21 days or less often than every 35 days
  • your periods last longer than 7 days
  • there’s a big difference between your shortest and longest menstrual cycle
  • you have irregular periods and you’re struggling to get pregnant
  • you have irregular periods and you aren’t ovulating
  • you also experience other symptoms such as pain and heavy bleeding
  • you have symptoms commonly associated with PCOS – acne, weight gain, hair in unwanted places 

There might not be anything wrong, but it’s a good idea to get checked out to see what the cause might be. You might be referred to a specialist called a gynaecologist if you need any tests or treatment.