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What Are Irregular Periods?

Your menstrual cycle doesn’t always work like clock. While some women get their periods right on schedule every 28 days, other women’s cycles aren’t so predictable. At least 30 percent of women have irregular periods during their childbearing years. While an irregular cycle is not usually a problem, it can occasionally signal health complications.

A period, or menstruation, is the part of the menstrual cycle in which the endometrium, which is the lining of the uterus, is shed. This appears as bleeding from the womb that is released through the vagina. Periods usually start during puberty, between the ages of 10 and 16, and they continue until menopause, when a woman is 45- to 55-years old.

Irregular periods, also called oligomenorrhea, can occur if there is a change in contraceptionmethod, a hormone imbalance, hormonal changes around the time of the menopause, and endurance exercises. Treatment for irregular periods during puberty and around the menopause is not usually necessary, but if irregular periods occur during the reproductive years, medical advice may be necessary.


The absence of periods (or amenorrhoea) usually occurs because an egg is not produced in the ovaries. The most common causes of absent periods are:

  • not having started puberty
  • pregnancy
  • breastfeeding
  • menopause

There are several other factors that may cause your periods to stop or to become lighter or less frequent, such as:

  • excessive exercise
  • being underweight or excessive dieting
  • feeling upset or stressed
  • a hormonal imbalance

Are Irregular Periods Dangerous?

A missed or irregular period may be the first clue that you have a condition that needs medical attention. If you have consistently irregular periods, you should be evaluated for PCOS. PCOS affects up to 10 percent of women of reproductive age. You should also be screened for thyroid disorders and other diseases that may be linked to irregular periods.

An irregular cycle can also make it more difficult to get pregnant, especially if you’re not ovulating every month. Your doctor can run tests to see if you’re ovulating. Women with irregular periods who are trying to have a baby are sometimes prescribed fertility drugs to increase ovulation. While it’s possible to get pregnant on your own if you have irregular periods, it’s still a good idea to be checked out by a doctor just to make sure that nothing serious is going on.


Treatment, if needed, will depend on the cause.

Puberty and menopause: Irregular periods that occur during puberty or as the woman approaches menopause do not usually need treatment.
Birth control: If irregular bleeding is due to contraception, and it continues for several months, the woman should talk to a health care professional about other options.
PCOS and obesity: In cases of PCOS, overweight, or obesity losing weight may help stabilize menstruation. A lower weight means the body does not need to produce so much insulin. This leads to lower testosterone levels and a better chance of ovulating.

Experiencing changes in the frequency or duration of periods is common in most women at some point in their lives. Any treatment or investigation of irregular or light periods will depend on the likely cause. There may, for example, be no need for treatment if you are nearing the menopause as irregular periods are common during this time.