Are irregular periods normal? 10 common causes and when to see a doctor

• Irregular periods include a shorter or longer cycle than normal, missed periods, and heavier flows.
• Common causes of irregular periods include stress, certain medications, birth control, and PCOS.
• If there are irregularities in your cycle, go to a doctor as it could be an underlying condition.

An estimated 9% to 14% of women will experience irregular periods at some point in their lifetime. In fact, about one-third of visits to the gynecologist are due to this problem.

Normally, your period should last between two to seven days and occur every 25 to 35 days. An irregular period is when the length or frequency of your periods is disrupted.

Signs you may have an irregular period include:

• A cycle shorter than 21 days (polymenorrhea) or longer than 35 days (aka oligomenorrhea)
• Amenorrhea, or when you miss one or more periods
• Unpredictable periods
• A lighter or heavier flow than normal
• A period longer than seven days
• Unusual PMS symptoms for you, such as increased anxiety or depression

Important: Go to a gynecologist if there has been a change in your cycle. For instance, if you are suddenly skipping several months or bleeding for three weeks straight, it could indicate something more serious such as a hormone imbalance or a thyroid condition.

While you should speak to a gynecologist about any unusual changes to your menstrual cycle, an irregular period isn't always a cause for alarm. In fact, frequent culprits for an irregular period include stress, birth control, or weight fluctuations.

Here are ten of the most common causes for an irregular period.

1. Stress

Your body will shut down your ability to ovulate and become pregnant when you're under heavy stress, says Taraneh Shirazian, MD, a gynecologist at NYU Langone Health.

That's because stress affects your hypothalamus. The part of the brain that helps control sleep, your emotional response to stress, and the release of hormones that induce your period.

Now, the more stress you're under - whether it's physical, like from an illness, or psychological like from anxiety - the greater your chances are that you'll experience irregular periods.

In fact, a small 2015 study of highly stressed college-aged participants found almost 86% had irregular menstrual cycles.

2. Eating disorders

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Eating disorders, such as bulimia, anorexia, or binge eating disorder place your body under physical distress, thereby affecting your hypothalamus, says Shirazian. This can disrupt the release of hormones during your menstrual cycle and cause infrequent or no periods, says Erin Higgins, MD, a gynecologist at Cleveland Clinic.

A large 2014 study on binge eating and menstrual dysfunction found women who reported lifelong binge eating were more likely to have amenorrhea, or an absence of menstruation, than women without binge eating disorder.

3. Birth control

Depending on the type of hormones in your birth control, you may experience either more or less bleeding, says Denise Johnson, MD, an obstetrician-gynecologist at the Women's Health Institute at UT Health Austin. For example:

• Pills with estrogen and progestin may cause spotting between cycles or irregular bleeding during the initial few months.
• Progestin-only methods, like the mini pill, injections, or implants, will thin the lining of your uterus, leading to less bleeding or a complete absence of your period. It may also cause spotting.
• Copper IUD may initially cause heavier periods or spotting between periods.
• Hormonal (progesterone) IUD may cause spotting between periods for the first three to six months, followed by a lighter or absent period.

4. Endometriosis

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Endometriosis, which affects 11% of American women, is a disorder that causes excess tissue to grow outside of your uterus.

Therefore, when it comes time for your period, there's more tissue for your body to shed, which often causes longer, and heavier periods that come more frequently (less than 28 days between periods). You may also experience spotting between periods.

Endometriosis is also typically accompanied by sharp, stabbing, or aching pain, especially in the lower abdomen, pelvis, and lower back.

5. Uncontrolled diabetes

Diabetes affects around 10.5% of Americans. When the condition is uncontrolled, meaning your blood sugar levels are too high, you can experience irregular and abnormal ovulation which results in hormonal disruption and irregular periods.

6. Pelvic Inflammatory Disease

Pelvic inflammatory disease, or PID, is an infection in the female reproductive organs, such as the uterus, fallopian tubes, and ovaries. It affects around 5% of women in the United States.

The inflamed tissue can cause infrequent bleeding and pain in the lower abdomen or pelvis, says Johnson.

Other side effects of PID include abnormal discharge, fever, and pain during intercourse and urination. See a gynecologist if you experience any of these symptoms.

7. Uterine polyps or fibroids

Uterine polyps and fibroids are growths on the inner wall of the uterus.

Polyps, which afflict 24% of women in their lifetimes, can range from a few millimeters in size to several centimeters and can cause spotting, says Johnson.

Note: Polyps are normally benign, and if they're small they may resolve on their own. However, larger growths can be cancerous or lead to cancer, in which case your doctor will likely remove the polyps. Cancer in polyps is not common in premenopausal people.

Meanwhile, fibroids, which about 20% to 80% of women will develop during their reproductive years, can cause heavy or unusually long menstrual cycles. They can grow to more than 8 inches. But, unlike polyps, fibroids are less likely to lead to cancer.

8. Polycystic Ovarian Syndrome (PCOS)

PCOS is a hormonal disorder that affects around 5% to 10% of women in the US and causes higher than average levels of the hormone androgen. This can prevent ovulation resulting in missed or irregular periods.

Other symptoms of PCOS include:

• Male-pattern baldness
• Weight gain
• Infertility
• Excess body hair

9. Certain medications

Some medications may cause increased bleeding or frequency of bleeding during your menstrual cycle. These include:

• Hormone therapy
• Chemotherapy
• Blood thinners, such as Aspirin
• Ibuprofen and other NSAIDS
• Thyroid medications
• Certain antidepressants or antipsychotics

10 Uterine or cervical cancer

Uterine or cervical cancer will typically cause more frequent menstrual bleeding or spotting, says Johnson. The irregular bleeding could be coming from a lesion in the cervix (cervical cancer) or from an overgrowth of cells within the uterus (uterine cancer). But if you are experiencing irregular bleeding, it is most likely coming from some other benign issue and not cancer, says Johnson.

Note: Uterine cancer is more common in perimenopausal/postmenopausal women. Vaccination and appropriate screening with a Pap smear is the best prevention for cervical cancer.

Risk factors for cervical cancer include:

• HPV infections
• Becoming sexually active at a young age and/or have multiple sexual partners
• Having a sexual partner who has had multiple sexual partners
• Smoking
• Problems with the immune system
• Long-term use of oral contraceptives
• Multiple pregnancies
• A history of chlamydia

Can you get pregnant with irregular periods?

While irregular periods don't always indicate an infertility issue, they can make becoming pregnant more difficult as you're not ovulating regularly, says Johnson.

If you are trying to get pregnant with an irregular period, it's important to track your ovulation by:

• Charting your cycle
• Tracking your basal body temperature, which will spike around ovulation
• Checking cervical mucus, which will be more plentiful, stretchy, and clear as you near ovulation

Note: You can also use ovulation predictor kits and fertility monitors. An ovulation predictor kit will alert you when there's an increase of the luteinizing hormone in your urine, which means you are ovulating.

Insider's takeaway

Menstrual cycles are different for everyone. While the average period typically lasts two to seven days and occurs every 25 to 30 days, people may also experience irregularities. These normally show up as shorter or longer cycles, missed periods, or overall unpredictability.

Common causes for irregular periods include taking birth control, stress, and disorders such as uncontrolled diabetes or PCOS. If you notice any unusual changes in your menstrual cycle, it's a good idea to consult your gynecologist or another medical professional to better understand what's going on.

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