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Why is my period irregular and what does it mean?

Some change in the length of your menstrual cycle is not uncommon. If you have one month that’s a few days shorter or longer than another, it’s probably nothing to think twice about. 

And, at different stages of life, irregular cycles are really natural, for example, when you first get your period, close to menopause, after pregnancy and when starting or stopping hormonal contraceptives. These are key times where periods might happen randomly.

The length of a monthly cycle also changes as you get older. For many menstruating people, periods become shorter during the 30’s and 40’s, and can become irregular as you head into perimenopause and menopause (when your body stops making as much estrogen and progesterone).

Outside of these times however, if your cycle is inconsistent, this can be a sign of something else going on.

Is my cycle irregular?

A cycle is considered to be medically irregular if: 

  • As anadolescent (if you’re between 10 and 19 years old), your cycle is outside of 21-45 days
  • As anadult (20 years of age and above), your cycle is outside of 24-38 days and varies more than 7-9 days between cycles (for example if you have one cycle that is 27 days long and then the next month’s cycle is 42 days long).
  • Periods that stop for more than 90 days (and you’re not pregnant, nearing menopause or discontinuing hormonal contraception).

Why does this happen?

There’s a lot that needs to happen in your body in order to have a cycle. A complex process of hormone changes that can become imbalanced by genetics, diet, exercise, stress, and certain medical conditions.

Some common causes of an irregular cycle are:

Chronic stress

Stress wreaks havoc on hormones. Increased stress hormone levels can communicate to your body that it’s not an optimal time for you to get pregnant (or to have a cycle). 

From an evolutionary perspective, this is nature’s way of trying to ensure that a baby is conceived and born into safety and security. 

Low body fat and / or intensive exercise

Sex hormones (which control your cycle) are stored within body fat. If you have low body fat this can mean lower levels of estrogen and an irregular or missing cycle. 

Similarly, for folks who are elite athletes, low body fat and exercise-related hormone changes can lead to an irregular cycle.

Polycystic ovary syndrome (PCOS)

A common condition affecting up to 1 in 10 girls and womenaged between 15 and 44, PCOS affects hormone balance and commonly causes irregular periods, ovarian cysts, excess facial and body hair and mood changes. 

PCOS can also impact fertility because of its effect on your menstrual cycle. If you think you might be experiencing PCOS, many folks find a conversation with their doctor helpful. Your doctor can help to work out exactly what is happening for you and to come up with a treatment plan to manage symptoms and support fertility.

Sleep disorders like Delayed Sleep Phase Syndrome

Studieshave shown a connection between Delayed Sleep Phase Syndrome and irregular periods. Sleep plays a huge role in hormone production and regulation and without enough quality sleep it’s easy to get out of balance.

If you’re struggling with an irregular cycle, it can be helpful to have a chat with your GP to find out what might be causing it. 

Tracking your cycle is a great way to get data that you can show your GP to help pinpoint possible issues. 

Download the YourCycle app for personalised information on everything to do with your cycle. It’s completely free and always will be.