Irregular periods

Are irregular periods a cause for concern?


The average menstrual cycle lasts for 28 days. However, each woman is different, and menstrual cycles can last for anytime between 24-35 days. Your period is considered irregular if it doesn’t arrive on time each month, regularly arriving late or early. It might only vary within a couple of days which is not a cause for concern. 


How do I know if my periods are irregular? 

A normal menstrual cycle lasts for roughly 28 days and may be a couple of days longer or shorter than this. If your cycle is usually 28 days long, it would start on day one of your period and end 28 days later, which will be the day before your next period. A period usually lasts between 3-7 days and causes you to lose 3-5 tablespoons of menstrual blood. 

If you never know when you’re going to get your period, have more or less than one per month or excessively light or heavy bleeding, then this is considered an irregular period. 

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What causes irregular periods? 

There are several possible causes for irregular periods. These include: 

  • Hormonal changes in the body like puberty or the menopause 
  • Early stages of pregnancy 
  • Hormonal contraception 
  • Stress 
  • Excessive exercise 
  • Weight loss or weight gain 
  • Polycystic ovary syndrome 
  • Thyroid problems 

When should I see my GP? 

If you are on progestogen-only forms of hormonal contraception, irregular periods are a possible side effect and therefore not a cause for concern. This includes the mini-pill, implant, injection and hormonal IUS (coil). The combined pill, ring or patch usually regulates your period, but if you’ve run two packs or patch/ring cycles back to back, this will disrupt your usual cycle. 

It’s quite normal for your periods to be irregular when you are still going through puberty or are approaching the menopause. If you have experienced a very light, short period or have missed one altogether, you should take a pregnancy test to ensure that you’re not pregnant. 

If none of these circumstances apply to you, you should see your GP as irregular periods indicate a hormonal imbalance or underlying medical condition. If stress, exercise, or weight loss are its cause, then this will need to be addressed. 

How are irregular periods treated? 

Most of the time, treatment is not necessary. Suppose you are using a contraceptive like the implant and the irregular bleeding or other side effects are bothering you, you can have it removed and try a different contraceptive instead. 

The combined pill is often prescribed for polycystic ovary syndrome to regulate the hormones and trigger a period. For an underactive thyroid, you will likely be prescribed with thyroid hormones. 

Lifestyle changes will be recommended if excessive exercise, stress or weight loss is the cause. If you are struggling to manage stress, you may be referred to stress management resources or classes or may benefit from cognitive behavioural therapy. If excessive weight loss results from an eating disorder such as anorexia or bulimia, this will require different treatment. These are both serious mental health conditions. 

Will irregular periods affect my chances of having a baby? 

If your periods are irregular, this causes you to ovulate less often, which means it can take longer to get pregnant. This does not mean you can’t have a normal, healthy pregnancy, however. There are things you can do to increase your chances of getting pregnant: 

  • Have sex regularly (every 2-3 days)
  • Make sure any medical conditions are under control 
  • Maintain a healthy weight 
  • Don’t smoke or drink alcohol 
  • Limit the amount of alcohol your partner drinks 
  • Track your cycle so that you can have sex around the time you ovulate



NHS > Irregular Periods
Web MD > Why is My Period So Random?

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