Irregular periods are not always a sign of a problem.
Signs of an irregular period
The gap between your periods starting (your menstrual cycle) can range from 21 to 35 days. The average menstrual cycle is 28 days. But it is normal for it to be a bit shorter or longer than this.
Your periods are irregular if the gap between your periods starting keeps changing. It may come earlier than 21 days or later than 35 days.
Your periods are regular if you have a similar number of days between periods. But it can vary by a few days each time.
It is more likely for your periods to be irregular:
- during puberty
- when you are nearing menopause
Using an app or a diary to keep track of your periods can help you see if they are irregular.
Causes of irregular periods
Common causes of irregular periods include:
- puberty - your periods might be irregular for the first year or 2
- the start of the menopause (usually between ages 45 and 55)
- pregnancy - take a pregnancy test to rule this out
- some types of hormonal contraception - such as the pill or intrauterine system (IUS)
- losing or gaining a lot of weight
- exercising too much
- stress
- medical conditions - such as a problem with your thyroid or polyendocrine metabolic ovarian syndrome (PMOS)
You do not need to get medical advice if you have always had irregular periods or you are still going through puberty.
Non-urgent advice: Contact your GP if:
- your periods suddenly become irregular and you're under age 45
- your periods usually last longer than 7 days
- there is a big difference (at least 20 days) between your shortest and longest menstrual cycle
- you have irregular periods and you are struggling to get pregnant
There might not be anything wrong, but it is a good idea to get checked out to see what the cause might be.
Treating irregular periods
Your GP may refer you to gynaecologist (a women's health specialist) if you need any tests to find out what is causing your irregular periods. If you need treatment, it will depend on the cause.
Trying for a baby if you have irregular periods
It can be more difficult to get pregnant if you have irregular periods because you might not ovulate (release an egg) regularly.
It can help to have sex every 2 or 3 days throughout your cycle without using contraception. You do not need to time sex around ovulation.
If you are struggling to get pregnant naturally, you may need:
- hormone medicine
- fertility treatment
Your GP can refer you to a regional fertility hub for tests and treatment.
Content supplied by the NHS and adapted for Ireland by the HSE
