Menstrual Health

Aug 23, 2021

Causes behind irregular periods

There are a few causes for irregular periods. Not all warrant immediate concern, but some could be indicative of underlying health conditions

For a second, let’s imagine that you’ve skipped your period this month. The first emotion you probably feel is relief -- relief that you don’t have to worry about painful cramps, changing period protection or staining your duvet. On the flip side, you probably feel a sense of unease and worry at the back of your mind. Why was your period late? Brushing aside the possibility that you may be pregnant, there are a few other reasons for your periods to suddenly become irregular. Not all warrant immediate concern, but some could be indicative of larger, underlying health conditions. We firmly believe that understanding the inner workings of your body can help you take control of your menstrual health, so let’s get started.

What constitutes an Irregular Period (Oligomenorrhea)?

Per the NHS, your periods are said to be irregular, if the the gap between your periods starting keeps fluctuating.  [1] While some variability is to be expected, the majority of your cycles within a six month period should fall within the same day range. The average length of a menstrual cycle is about 28 days, but it could be shorter or longer for different individuals. Usually a normal menstrual cycle falls between 21 to 35 days. [2] In order to determine if your period is irregular, it is important to pay attention to what is the normal length of your menstrual cycle and observe any deviations. 

The definition of irregular periods can also vary depending on your age. For instance, if you are going through puberty and have just started your first period, it is normal for your cycle to be irregular. In fact, per Cleveland Clinic, it can take anywhere up to 3 years after your first period for your cycle to become regular as your hormones balance out. [3] On a similar note, as you approach your perimenopause in your late 30s - early 40s, it is normal for your cycle to start becoming irregular as your ovaries produce less estrogen. (You can read more about menopause here). 

If you’ve just given birth, your period might also look different to what it was previously. Some women see longer or more painful periods after having a baby, while others notice improvements in their cycles. Many women also don’t menstruate while breastfeeding. [4] In this situation, however, it is advisable to consult your doctor to make sure that the change in your periods isn’t stemming from any rare complications.

Typically, if your period suddenly becomes irregular during the reproductive years, medical advice may be required. 

Causes of Irregular Periods

Aside from certain age-specific nuances, there can be other causes behind your periods becoming irregular. Generally speaking, these causes can be bucketed lifestyle factors and other, more serious, underlying medical conditions. 

Lifestyle factors: 

Your menstrual health is inextricably linked to your sleep, mental health, nutrition and exercise habits. Sudden changes in your lifestyle or poor quality of living can negatively impact your period cycles, throwing them out of sync. If you notice deviations in your cycle length, do not panic, but instead begin by taking a look at your current lifestyle for explanations. 

Disrupting your sleep cycle, working late into the night and experiencing jet lag post travel, could all be potential causes of irregular periods. [5]  Looking at surveys filled out by nurses, industrial workers and flight attendants, working rotating or night shifts was associated with greater menstrual irregularities and health problems than working other shifts. [6] In fact, female health and physiology seems to be particularly vulnerable to disruption in circadian rhythms, making it important for you to ask yourself if your sleep habits are driving changes in your menstrual health. 

Emotional changes are also variables that need to be considered when determining the reason behind your irregular cycle. Persistent or chronic stress can contribute to irregularities in your cycle, with research indicating that “as chronic stress increases, all women, irrespective of their level of dispositional resilience, experience an increased risk of menstrual cycle irregularity.” [7] There also seems to be individual variability in the disruption of period cycles, with some women much more sensitive than others to the same amount of stress.

Lastly, physical changes can be key drivers behind irregular cycles including sudden changes in weight, poor eating habits and partaking in intensive exercise. It is also important to note that aside from weight gain, excessive dieting (not getting sufficient calories) too can be a cause for irregular period cycles. 

Medical conditions:

After you’ve inspected your lifestyle to determine causality, it may be necessary to consider the possibility of underlying medical conditions. Common suspects include Polycystic Ovarian Syndrome (PCOS), Thyroid disorders, Uterine fibroids, Uncontrolled diabetes, Eating disorders (such as bulimia), certain medications (including anti-epileptics and antipsychotics), Hyperprolactinemia and Primary Ovarian Insufficiency (menopause before the age of 40).We’ve written extensively about would recommend you checking those blogs out, especially if you also experience excess facial hair. 7 out of 10 women with PCOS go undiagnosed. Sometimes going off birth control can also cause changes to your period cycles. 


When should you visit a doctor?

Since irregular menstruation is typically caused by a variety of factors, there is no one-size-fits-all approach. We recommend first looking at your age and identifying possible reasons for irregular periods that are normal. This includes puberty and menopause. After which, it is prudent to consider any lifestyle changes that may have caused a disruption in your cycle. If however, you notice a sustained absence of menstrual cycles or long-term irregularity, it is best to visit your medical provider to rule out any other causes. As general rules of thumb, you should consult a doctor if:  

  • Your periods suddenly become irregular and you're under the age of 45
  • You have skipped your period 3 months in a row, without being pregnant or in menopause
  • The length of your cycle changes by 7-10 days 
  • Your bleeding lasts longer than 7-10 days
  • Your cycles fall out of the 21-35 day range

There may not be anything to panic about, but it can help ease your worries and pinpoint ways of treatment.


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