When to Worry About Missed or Irregular Periods

Polycystic ovary syndrome (PCOS) affects 4 to 20% percent of women of childbearing age. This condition is characterized by higher than normal levels of testosterone, creating an imbalance of female sex hormones.

PCOS is the most common cause of ovulatory infertility. Infrequent irregular periods (oligomenorrhea) or the absence of periods (amenorrhea) is a common symptom of PCOS. However, there are many things that can cause irregular periods, and PCOS is not the only one.

A woman talking to her a doctor
Tetra Image / Getty Images

Possible Causes

Pregnancy is the most common cause of not having your period—and this is normal. Periods should resume within a few months after having a baby, and they can be irregular or delayed while breastfeeding.

The medical causes of irregular or absent periods are many. PCOS is one of the conditions your healthcare provider may consider if you have ongoing, persistent menstrual irregularities.

PCOS is typically diagnosed when a woman has at least two of three characteristic symptoms:

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

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.

If you exercise excessively, lose a significant amount of weight, or are under a lot of stress, this can affect your periods as well. Medical conditions such as hypothyroidism (low thyroid function), hyperthyroidism (excessive thyroid function), or elevated prolactin levels (due to pituitary disease, for example) can also cause missed or absent periods

You should make an appointment to see a healthcare provider if you have missed at least three menstrual periods in a row or if you are 15 or older and have not yet menstruated.

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—so the lining is exposed to unopposed estrogen. This causes the endometrium to grow much thicker than normal and contributes to the increased risk of cancer.

Keep in mind that this does not apply if you are 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 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 you should see a 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. Although not indicated for this reason, metformin can also help some women to regulate their cycle.

Some people who have PCOS can experience regular menstrual cycles through weight loss, changes to their eating, and exercise. In addition, the dietary supplement inositol has been shown to be helpful to 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.

Was this page helpful?
5 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.
  1. Deswal R, Narwal V, Dang A, Pundir CS. The prevalence of polycystic ovary syndrome: A brief systematic review. J Hum Reprod Sci. 2020 Oct-Dec;13(4):261-271. doi:10.4103/jhrs.JHRS_95_18

  2. The Practice Committee of the American Society for Reproductive Medicine. Current evaluation of amenorrhea. Fertil Steril. 2004;82 Suppl 1:S33-9. doi:10.1016/j.fertnstert.2004.07.001

  3. Parazzini F, La vecchia C, Bocciolone L, Franceschi S. The epidemiology of endometrial cancer. Gynecol Oncol. 1991;41(1):1-16. doi:10.1016/0090-8258(91)90246-2

  4. Naderpoor N, Shorakae S, De courten B, Misso ML, Moran LJ, Teede HJ. Metformin and lifestyle modification in polycystic ovary syndrome: systematic review and meta-analysis. Hum Reprod Update. 2015;21(5):560-74. doi:10.1093/humupd/dmv025

  5. 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