Irregular Periods (Amenorrhea)

Irregular periods, or amenorrhea, are menstrual periods that aren't "regular." You may miss a period, have periods that are shorter or longer than normal, or heavier or lighter. There may be additional problems, too, that aren't due to pregnancy, breastfeeding, or menopause.

Many people experience irregular periods during their lifetime for a variety of reasons.

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On this page:  

• What Are Irregular Periods?
• What Are the Symptoms of Irregular Periods? 
• How Do You Diagnose Irregular Periods? 
• How Do You Treat Irregular Periods?

What Are Irregular Periods?

Doctors define irregular periods as changes to a person’s normal menstrual cycles or periods.

Irregularities may include:

• Missing a period.
• Having a shorter or longer period than normal.
• Having a heavier or lighter period than normal.
• Having other problems not caused by pregnancy, breastfeeding, or menopause.

Irregular periods are also known as amenorrhea — the absence of normal periods.  

The menstrual cycle is the series of hormonal changes that occur in the body to prepare for a possible pregnancy. Most people start their period between the ages of 11 and 15, and most menstrual cycles occur every 21 to 35 days.

Menstrual irregularities — irregular periods — are often a symptom of another condition. 

There are two classifications of amenorrhea: 

• Primary amenorrhea — A person hasn't started their period by age 16. This is different from having infrequent or light periods, which is common during the first couple of years of menstruation.
• Secondary amenorrhea — A person who's previously had periods stops having a period for more than three to six months.

Ovulation can still occur during an irregular cycle, so you can still become pregnant even if you're having irregular periods. It's important to take birth control measures if you're having sex but don’t want to become pregnant.

How common are irregular periods

About 14% to 25% of menstruating people will experience irregular periods. But amenorrhea that isn't linked to pregnancy, breastfeeding, or menopause occurs in only 5% of menstruating people. 

What are the types of irregular periods?

Period irregularities may fall into a series of categories:

• Amenorrhea — When you don't get your period before age 16 or when your period stops for three months or more, but you're not pregnant.
• Cycle-to-cycle variation — Menstrual cycles that vary by more than 20 days between each cycle. 
• Dysmenorrhea — Painful periods with severe cramps.
• Intermenstrual bleeding — Spotting between periods.
• Menorrhagia — Heavy periods.
• Oligomenorrhea — Periods occurring more than 35 days apart.
• Polymenorrhea — Periods occurring less than 21 days apart.
• Prolonged menstrual bleeding — Periods that regularly last for more than eight days.
• Shortened menstrual bleeding — Periods that last for less than two days.

What causes period irregularities?

Period irregularities can be a natural part of life for menstruating people as a result of hormone changes, pregnancy, breastfeeding, or menopause. 

But they can also indicate another health problem, such as:

• Absence of a uterus or ovaries or abnormal pelvic organs.
• Damage to the ovaries from chemotherapy or radiation treatment for cancer.
• Chronic diseases, such as anemia, congenital heart disease, diabetes, or thyroid disease.
• Developmental problems of the uterus or vagina.
• Eating disorders, such as anorexia, bulimia, or fad dieting.
• Fragile X-associated primary ovarian insufficiency (FXPOI), a condition that causes a loss of normal ovarian function in women under 40.
• Inherited diseases, such as Turner syndrome.
• Intense exercise.
• Malnutrition.
• Ovarian failure or premature menopause.
• A pituitary tumor, which can cause the pituitary gland to produce abnormal levels of certain hormones.
• Polycystic ovarian syndrome (PCOS), a condition that causes hormonal imbalances and interferes with ovulation.
• Problems with the structure of the vagina, such as an imperforate hymen, a condition that occurs when skin covers the opening of the vagina. 
• Stress.
• Very low or very high body weight.

Your menstrual cycle is the result of hormonal changes in your body produced by the hypothalamus and pituitary glands in the brain, the ovaries, and the uterus. Disruptions to the menstrual cycle can arise at every level.

When the hypothalamus fails to release the hormone GnRH (gonadotropin-releasing hormone) in a normal manner, it can cause hypothalamic amenorrhea. This may be due to a low body weight, increased stress levels, or strenuous exercise.

In a normal menstrual cycle, the release of GnRH by the hypothalamus will trigger the pituitary gland to release the hormones FSH (follicle-stimulating hormone) and LH (luteinizing hormone). Problems with other hormones located in the pituitary gland, such as TSH (thyroid-stimulating hormone) and prolactin, can cause menstrual irregularities, too. 

Irregular period risk factors and complications

Irregular period risk factors

You may be at an increased risk of an irregular period if you: 

• Are obese.
• Are underweight.
• Exercise excessively.
• Have a change to the FMR1 gene on your X chromosome, which causes Fragile X Syndrome.
• Have an eating disorder, such as anorexia or bulimia.
• Have a family history of early menopause.
• Have a family history of menstrual irregularities.

Irregular period complications

If you're pregnant and had menstrual irregularities before you conceived, you may be at a higher risk of developing preeclampsia during your pregnancy or having a low-birth-weight baby.

Because irregular periods may cause a disruption to/lack of ovulation, some people may have a more difficult time getting pregnant. Consult with your doctor and a fertility specialist if you have period irregularities and are trying to get pregnant.

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What Are the Symptoms of Irregular Periods? 

The main symptom of period irregularities is a missed period.

Irregular periods may also cause:

• Changes in how long your period lasts, how often you menstruate, or how heavy your flow is.
• Changes in vision.
• Growth of excess facial hair.
• Loss of hair.
• Headaches.
• Milky discharge from your breasts.
• Underdevelopment of breasts.

When should I see a doctor about my irregular period symptoms?

A regular menstrual cycle is a function of your overall health. If you miss a period for reasons other than pregnancy, breastfeeding, or menopause, you should talk to your doctor. It may be the result of another health problem.

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How Do You Diagnose Menstrual Irregularities?

To diagnose menstrual irregularities, your women's health provider will first evaluate your medical history and perform a physical exam.

Your doctor will want to know:

• How old you were when you first started your period.
• If you're sexually active.
• If you're pregnant.
• If you've recently had significant weight changes.
• How much you exercise.
• What your menstrual cycles are typically like.

If you're over 16 and have never had your period, your doctor may also conduct a pelvic exam to look for signs of puberty.

It's helpful to keep track of your periods and share this tracking with your doctor. You should record when a cycle starts, how long it lasts, and any problems that you experience during the cycle. The first day of menstrual bleeding marks the first day of your cycle.

Your doctor may also order tests to figure out why your periods are irregular.

Tests to diagnose irregular periods

If you're sexually active, your doctor will most likely ask you to take a pregnancy test.

Other tests for irregular periods may include:

• Androgen test — High levels of androgens in the blood (also called “male hormones”) may indicate PCOS.
• Chromosome evaluation — Also known as a karyotype, this test analyzes whether any chromosomes are missing, in excess, or rearranged.
• CT scan — This scan combines many cross-section x-ray images to make a 3D image and determine if your kidneys, ovaries, and uterus appear normal.
• Hormone challenge test — Your doctor will prescribe a seven- to 10-day course of medication to try to trigger your period. This will help your doctor determine if a lack of estrogen is the cause of your irregular periods.
• Hysteroscopy — A thin camera that is inserted into your vagina and through your cervix to visualize the inside of your uterus.
• MRI — Radio waves visualize your brain or reproductive organs.
• Ovary function test — Thisblood test measures your FSH and LH levels to determine if your ovaries are functioning properly. Your doctor may also measure your AMH (anti-Mullerian hormone) levels, as abnormal AMH levels are associated with PCOS, menopause, and primary ovarian insufficiency (improper function of the ovaries before age 40).
• Screening for premutation of FMR1 gene — This can cause your ovaries to stop functioning properly and may be an indication of FXPOI.
• Thyroid function test — This blood test measures your thyroid-stimulating hormone (TSH) level to determine if your thyroid gland is overactive (hyperthyroidism) or underactive (hypothyroidism).
• Ultrasound — This test uses soundwaves to produce pictures of your reproductive organs.

Sometimes, no specific cause for period irregularities may be found. This is called idiopathic amenorrhea.

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How Do You Treat Irregular Periods?

Treatment for your irregular periods will depend largely on why they're irregular. The goal of treatment will be to correct the underlying condition.

For example, if you have primary amenorrhea, your doctor may recommend waiting to see if your period begins. It's common for people with primary amenorrhea — especially those with a family history — to have delayed periods due to low hormone levels. 

But if your primary amenorrhea is due to a chromosomal or genetic problem, or you have a physical condition like an imperforate hymen, your doctor may recommend surgery.

Medicine for irregular periods

You may be prescribed hormone therapy to help to regulate your cycle. For instance, if you have secondary amenorrhea, birth control pills or other medication can regulate your hormones.

Or, you may be prescribed medication to alleviate symptoms of PCOS, or for estrogen replacement therapy (ERT) if your body isn't producing a normal level of estrogen during your menstrual cycle. 

A medication called Provera may be prescribed for a short time to try to induce a period. This can also help your doctor evaluate whether your ovaries are producing estrogen in a normal manner.

Lifestyle changes for irregular periods

If your doctor suspects that your period irregularities are the result of lifestyle factors, they may recommend that you:

• Adjust the frequency or intensity of your physical activity.
• Gain weight if you're severely underweight.
• Lose weight if you're severely overweight.
• Reduce your stress levels.

Surgery for irregular periods

Occasionally, surgery may be recommended for treating secondary amenorrhea. 

This may include:

• Hysteroscopic resection — Removes uterine scarring due to the surgical removal of fibroids, a cesarean (C-section) delivery, or a dilation and curettage (D&C). 
• Removal of a pituitary tumor — Although noncancerous, pituitary tumors disrupt the release of normal hormones and may result in vision loss as they grow. If a pituitary tumor doesn't respond to medication to shrink it, your doctor may remove the tumor through your nose and sinuses. Radiation therapy is also sometimes used to shrink the tumor.

By UPMC Editorial Staff. Last reviewed on 2024-09-05.