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Causes of irregular periods: Understanding your cycle and what disrupts it

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Posted by Alex Daly on Aug. 5, 2019

Have you missed a period? Or maybe two? If so, you may want to see a doctor. 

While there are times in life when period irregularity is natural — such as perimenopause (the time leading up to menopause) or when you’re a pre-teen or teenager new to menstruation — experiencing changes in your period is a reason to take a closer look at your cycle. If you are still young enough to be menstruating regularly, but find that your periods are no longer happening like clockwork, read on for more information about the possible causes and treatments, as well as signals that it’s time to make an appointment with your doctor. 

What do healthcare professionals consider an irregular period?

Before exploring the causes of irregular periods, it’s important to take a look at what is typically considered to be an irregular cycle. Your menstrual cycle is counted from the first day of your last period to the first day of your next period. Typically, a woman’s cycle is 28 days long — but it may be a bit shorter or longer and still be considered “regular.” Most healthcare professionals consider a woman’s period regular if it comes once every 24 to 38 days

As mentioned though, there are exceptions to this regularity. The Department of Health and Human Services says there are two groups of women for whom irregular periods are considered normal: teenage girls and perimenopausal women. Teenagers can expect their periods to be irregular for the first few years before falling into a regular pattern, while perimenopausal women typically find that their menstrual cycles become irregular while transitioning to menopause (the eventual end of menstruation). This process usually happens for women in their late 40s or early 50s, but differs from woman to woman. 

In case you hear these terms or see them mentioned in your medical charts, amenorrhea is the term that medical professionals use for the absence of a period for three menstrual cycles, and oligomenorrhea means having a period more than 35 days apart.

What are the causes of irregular periods? 

The National Institute of Health says there are different reasons your menstrual cycle may become irregular. These reasons can include:

  • Perimenopause (which usually begins in your late 40s or early 50s)
  • Primary ovarian insufficiency (which is the loss of normal ovarian function before age 40)
  • Pregnancy 
  • Breastfeeding
  • Pelvic inflammatory disease (an infection of the reproductive organs)
  • Uterine fibroids (noncancerous growths of the uterus)
  • Eating disorders, extreme weight loss, or excessive exercising 
  • Polycystic ovary syndrome (an endocrine system disorder) 
  • Thyroid dysfunction
  • Cushing's syndrome (elevated levels of the hormone cortisol)
  • Obesity
  • Diabetes
  • Certain medications
  • Asherman syndrome (related to severe scarring of the lining of the uterus)

Studies also show that environmental stress, exposure to pollutants, and psychosocial stress can also play a role in creating hormonal imbalance and therefore disturb the menstrual cycle

No matter what, it is important to see a medical professional if you notice anything unusual about your period. A doctor can help you identify the cause behind your abnormal menstrual cycle. 

Should I track my period and any changes?  

Before you start to treat an abnormal period or see a doctor, it is a good idea to track your menstrual cycle so you can see what’s typical for your body. (It can be beneficial to track even your regular periods, too, so you know what your normal cycles are like.) You can use a period-tracking app or online tool, or simply a paper calendar or notebook. 

For several months, mark the start date of your period and how long your cycle lasts. Then, ahead of seeing your medical professional, try and answer the following questions: 

  • How many times have you missed a period? 
  • How many days does your cycle last?  
  • Is your cycle heavier or lighter than usual?
  • Do you have a period more than once a month, or bleed in between periods?
  • Are your periods painful? 
  • Have you noticed a change in your mood? 

Think back to recent years and what has been most typical or “normal” for you when it comes to your period and related symptoms. What has changed? Share this information (and your notes and observations) with your healthcare provider. 

What can you expect at your doctor’s visit? 

Your provider will take a look at your personal medical history, and then likely ask about your family to see if there is a history of irregular menstruation. Your doctor will probably ask about medications or vitamins you take, and do a physical examination. He or she may order blood tests as well. A pelvic ultrasound may be recommended to identify abnormalities of the uterus, cervix, or vagina.

How can a doctor treat irregular periods? 

After assessing your condition and the reasons behind your irregular periods, your doctor will decide on the appropriate treatment

Healthcare professionals may consider a number of possible treatment options for irregular periods.  

  • Cyclic progestin is used in premenopausal women who are otherwise healthy but for various reasons are not ovulating and making enough of the hormone progesterone. 
  • Oral contraceptives are often used in young women who have just started menstruating. They can also be used to treat polycystic ovary syndrome. 
  • Counseling and nutritional therapy can also be used if your irregular periods are caused by an eating disorder. 

If your doctor diagnoses menstrual irregularities caused by heavy unusual bleeding, he or she may decide to:

  • Insert a hormone-releasing intrauterine device
  • Use medication, such as those containing progestin, or nonsteroidal anti-inflammatory medications

Finally, surgery is another treatment method that doctors use to treat scarring or structural problems in the uterus or fallopian tubes. 

When should you see a doctor for irregular periods? 

It’s generally a good idea to see a doctor as soon as you notice a change in your cycle. It’s especially important to see a doctor if you’re confused or concerned about recent changes in your cycle or if you’re trying to conceive (irregular periods can make it more difficult to get pregnant, but your doctor can help you explore possible solutions). Additionally, if you think there’s a chance you might be pregnant, see a doctor as soon as possible. 

Other period-related reasons to see a doctor include:

  • Missing three or more menstrual periods a year
  • Getting your period more often than every 21 days
  • Getting your period fewer than every 35 days
  • Bleeding more than usual during your cycle
  • Having a period that lasts longer than a week
  • Experiencing more pain than usual during your cycle

There are many possible reasons behind irregular periods and many ways to treat them, so seeing a doctor can help determine the healthcare plan that makes sense for you. Book an appointment with a provider today. 

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