When to Worry About Missed or Irregular Periods

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Polycystic ovary syndrome (PCOS) affects between 4% and 20% of women of childbearing age. The condition is characterized by higher than normal levels of testosterone, which creates an imbalance of female sex hormones.

PCOS is the most common cause of ovulatory infertility. Infrequent, irregular periods (known as oligomenorrhea) and the absence of periods (amenorrhea) are common symptoms of PCOS. However, many things can cause irregular periods, and PCOS is only one of them.

This article explains the possible causes of irregular or absent periods, the risks and complications, and treatment options.

A woman talking to her a doctor
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Possible Causes

Most women experience irregular periods at some point in their life. You can consider your period irregular if it:

  • Comes more often, or more than once every 21 days
  • Comes less often, with 35 days or more between cycles
  • Varies greatly in length

An absent period is easier to define: It just doesn't show up. Pregnancy is the most common cause of not having a period. Periods should resume within a few months after having a baby, and they can be irregular or delayed while breastfeeding.

There are many medical causes of irregular or absent periods. PCOS is a chief cause. It is typically diagnosed when a woman has at least two of three accompanying symptoms:

  • High androgen levels, like testosterone, or physical signs of high androgens, like excessive body hair
  • Irregular menstrual cycles
  • Ovarian cysts


Being pregnant or having polycystic ovary syndrome (PCOS) are two leading reasons why women experience irregular or absent periods.

Other Reasons

If you are a teenager who has only recently gotten your first period, or if you're approaching menopause, you can experience irregular cycles because of hormone fluctuations. Menstrual irregularities may also be caused by an intrauterine device (IUD) or a recent change in an oral contraceptive.

Irregular or absent periods can also be triggered by:

Irregular or absent periods may cause you to worry, but you should do more than that: If you've missed at least three menstrual periods in a row, or if you're 15 or older and have not yet menstruated, it's time to make an appointment with your healthcare provider.


If you're approaching menopause, you may be correct to chalk up your menstrual irregularity to your "change of life." But it pays to be sure. Make an appointment with your healthcare provider anyway. Missed periods prior to menopause can be due to diabetes.

Risks and Complications

An occasional missed period is normal. However, not having a regular period can increase your risk of endometrial cancer.

All females have some levels of androgens (male hormones like testosterone). During a normal menstrual cycle, the endometrium is exposed to hormones, like estrogen, which cause the lining to proliferate and thicken. When ovulation does not occur, the lining is not shed, and progesterone doesn’t go up as it usually would. Then the lining is exposed to unopposed estrogen. This causes the endometrium to grow much thicker than normal and contributes to an increased risk of cancer.

Keep in mind that this does not apply if you're taking a birth control pill to treat PCOS, especially those designed to prevent you from getting your period more than once every few months. The pill keeps your hormone levels low and your endometrial lining thin, reducing your risk of endometrial cancer.

Symptoms of endometrial cancer include pelvic pain, bleeding between periods, pain during intercourse, and a watery or blood-tinged discharge. There are usually no other early warning signs, so see your healthcare provider even if your symptoms are mild.


There are many different ways to treat irregular or absent periods in PCOS, depending on your goals and health history. Some healthcare providers recommend oral contraceptives to balance out hormones and create a regular cycle. Metformin can help some women regulate their cycle.

Some people who have PCOS can experience regular menstrual cycles through weight loss, changes to their eating habits, and exercise. In addition, the dietary supplement inositol has been shown to help regulate periods and balance hormones in people with PCOS.

If your periods suddenly become irregular, talk to your healthcare provider. Further diagnostic testing and/or medical interventions could be necessary.


Pregnancy and polycystic ovary syndrome (PCOS) are two primary causes of an irregular or missed period. But sometimes the root cause lies somewhere else, like with elevated prolactin levels or thyroid disorders. Even a change in daily living activities can upset a normal menstrual cycle. Most women experience some bumps in their cycle, but it's time to call your healthcare provider if you miss three menstrual periods in a row.

A Word From Verywell

Few things can match the growing sense of panic you may feel as you wait...and wait some more...for an overdue period to arrive. Try to avoid getting stressed, and take comfort in knowing that an occasional irregular period is nothing to sweat. Even two periods shouldn't rattle you. But three missed periods? It's time to phone your healthcare provider.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  7. Morley LC, Tang T, Yasmin E, Norman RJ, Balen AH. Insulin-sensitising drugs (metformin, rosiglitazone, pioglitazone, D-chiro-inositol) for women with polycystic ovary syndrome, oligo amenorrhoea and subfertility. Cochrane Database Syst Rev. 2017;11:CD003053. doi:10.1002/14651858.CD003053.

By Nicole Galan, RN
Nicole Galan, RN, is a registered nurse and the author of "The Everything Fertility Book."