Having a menstrual cycle that “shows up” on time, every time, like clockwork is a luxury few women and people assigned female at birth get to enjoy. For many people, the ebb and flow of their menstrual cycles often feels more like unpredictable ocean waves rather than precise lunar cycles. If you find yourself double-checking your period tracking app or calendar on the regular, you’re definitely not alone. Irregular periods can be bewildering, but there's usually an identifiable reason for them.

Irregular periods can even be an early sign that something else might be going on, like an underlying medical condition or unhealthy lifestyle choice, so understanding the potential cause(s) of irregular periods is crucial to addressing any health and wellness concerns that might be throwing your period off track.

What is an irregular period?

Before diving into the various causes of irregular periods, let’s look at some examples the American College of Obstetricians and Gynecologists considers to be irregular menstrual cycles.

• You’re 15 and haven’t had a period.
• It’s been 3 years since breast development and you haven’t had a period.
• Your periods were regular but aren’t anymore.
• Your period arrives more often than every 21 days or less often than every 45 days.
• Your period comes more than 90 days apart.
• Your period lasts longer than 7 days.

The Reasons for Irregular Periods

Almost everyone with a uterus will experience an irregular cycle or two during their reproductive lifespans. If your periods are occasionally irregular, it’s usually nothing to worry about. However, if you’re consistently experiencing irregular periods, it’s a good idea to chat with your healthcare provider so she can help pinpoint the possible cause(s) and offer potential solutions or treatments. Sometimes, fairly simple lifestyle changes can make all the difference.

What follows is a list of some of the most common reasons your period might be irregular:

Hormonal Imbalance

Fluctuations in hormones, especially estrogen and progesterone, can impact the regularity of your menstrual cycle. Several conditions like PCOS (polycystic ovarian syndrome), thyroid disease, and premature ovarian insufficiency can lead to unpredictable hormone imbalances that can cause irregular periods.

Stress

Yep, good ole stress is a very common reason for irregular periods. It can lead to hormonal imbalances that might cause your period to be early, late, or skipped.

Extreme Weight Changes

Extreme weight loss or weight gain can disrupt your menstrual cycle. Being significantly underweight can cause your body to halt ovulation, which in turn causes missed periods. Being overweight can lead to excess estrogen production, which can lead to irregular menstrual cycles.

Excessive Exercise

While regular exercise is a great way to improve and maintain your health, there is such thing as too much of a good thing. High levels of physical activity, especially when combined with low body fat, can lead to irregular or absent periods.

Birth Control

Starting, stopping, or switching birth control methods can turn your menstrual cycle into a guessing game. Hormonal birth control methods, like pills, patches, injections, rings, and IUDs, can cause all kinds of irregular bleeding. Periods can become lighter, heavier, or even absent while your body adjusts to new hormone levels.

Puberty and Perimenopause

During puberty, it’s common for periods to be irregular while your body figures out how to balance the environment of new hormones. In a similar way, during perimenopause, the years leading up to menopause, periods can become unpredictable and irregular until they stop altogether.

Medications

Certain medications (besides hormonal birth control) can cause irregular periods as a side effect, including antipsychotics, antidepressants, and chemotherapy drugs.

PCOS (polycystic ovarian syndrome)

A condition characterized by excess androgen production and multiple ovarian cysts, PCOS can lead to irregular menstrual cycles among other symptoms, like weight gain, excessive hair growth, acne, and infertility.

Endometriosis

This condition, where tissue similar to the lining of the uterus grows outside of it and implants on other organs, can cause irregular periods along with painful periods and infertility issues.

Chronic Diseases

Chronic health conditions such as celiac disease (an immune reaction to gluten) or diabetes can greatly impact period regularity.

Lifestyle Factors

Our day-to-day choices, from what we eat to how much we sleep, can influence menstrual cycles. Poor diet, inadequate sleep, and high levels of stress can all lead to irregular periods. Another reminder of how interconnected our lifestyle choices and overall health are.

When should you see a doctor about irregular periods?

While occasionally irregular periods are usually normal, consistent irregularities should motivate you to make an appointment with your healthcare provider. Often, a potential cause and practical solution can be found. In fact, often, the solution is as simple as making a few smart lifestyle modifications. If a more serious underlying health condition is at play, your provider can help diagnose and treat that too.

By understanding and paying attention to your body's signals, like irregular periods, you're taking an important and empowering step toward improving and managing your reproductive and overall health.

If you’re experiencing irregular periods and want help diagnosing, managing, and treating the underlying condition or cause, sign up for Tia. Our team of clinic experts practice women-centric, whole-body, one-size-never-fits-all healthcare that will make you feel safe, seen, heard, and supported.