Irregular Periods Overview

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Irregular Periods Overview

Updated: 26-June-2022


Irregular periods is defined as having a regular cycle length of less than 22 days (called Polymenorrhea) or more than 35 days (called Oligomenorrhea).

This means a menstrual cycle length anywhere between 22 to 35 days is considered normal. Although in women aged 40-44, the range is slightly shorter, with regular cycle lengths from 23 to 30 days.
Source: Munster K, et al. (1992)

It is also not uncommon for a woman’s cycle to vary by a few days each time. However a large variation in blood loss during menstruation, or duration of periods, is considered irregular.

In extreme cases menstruation can also fail to occur for at least 6 months, known as amenorrhea.

Overall ovulation disorders are very common and present in 18-25% of couples who see a specialist for infertility treatment. This does not necessarily mean a woman is infertile. In fact it is common for women to experience incomplete or anovulatory cycles occasionally according to their age.
Source: Johnson M H (2018); Hull M G, et al. (1985)

incidence of three main types of menstrual cycle in women trying to conceive irregular periods fertilpedia
General incidence of anovulatory, normal and incomplete (short luteal phase) menstrual cycles in females aged between 10 and 50 years old.

On the other hand, women who have never had entirely normal cycles may be the result of some failure during maturation of the neuroendocrine system at puberty. For example, studies show women with long (oligomenorrhea) and normal cycles, have 5 times and 2 times higher levels of AMH respectively, compared to women with short (polymenorrhea) cycles. Although with age and decreasing AMH levels, regular menstrual cycles return for many of these women.
Source: Zhu R, et al. (2016); Dewailly D, et al. (2014)

However most Doctors will still advise against a wait and see approach with good cause. The fastest way to get pregnant with irregular periods is to diagnose the exact cause and treat accordingly. This restores a womans regular cycles and natural fecundability.

In women with normal cycles (aged under 35) the cumulative conception rate is approximately 50% after 2 cycles, and increases to 85%, after 6 months of trying to conceive.

Interestingly this rate of conception is similar for women with irregular cycles, once they manage to restore regular cycles, through medical intervention. However this result is not the same for every woman and depends on any findings by your Doctor or Specialist.


In women with irregular periods the most common signs and symptoms of early pregnancy are: nausea with or without vomiting, breast enlargement and tenderness, increased frequency of urination without pain and fatigue.

These symptoms begin to occur at 5 to 6 of gestation however a home pregnancy urine (hCG) test can generally confirm a positive pregnancy in women with irregular periods just 2 weeks after intercourse.

After which Doctors recommended women verify the positive urine test with a serum (blood) test, using a commercial or hospital based laboratory, to confirm their hCG levels (and pregnancy) as this is highly accurate (hCG detection level 1-2 mUI/mL).

Risks associated with Irregular Periods

Irregular periods have a range of effects on the body including:

  • Early Coronary Artery Disease believed to be a result of elevated cholesterol levels and low levels of estrogen affecting endothelial function, vascular resistance and nitric oxide production.
  • Endometrial hyperplasia leading to Endometrial cancer.
  • Germ cell tumors (Gonadoblastoma, dysgerminoma).
  • Low bone mineral density and bone mineral content leading to increased risk of stress fractures.
  • Impaired physical and sexual development, in long term cases beginning at puberty.
  • Premature death.

Source: Kiconco S, et al. (2021); Tsukahara Y, et al. (2021); Heather A K, et al. 2021; Dynnik V, et al. (2020); Wang Y X, et al. (2020); Ackerman K E, et al. (2015)

Causes of Irregular Periods

The cause of abnormal irregular periods fall into 5 main categories:

  • Hypothalamic-pituitary failure (Group 1)
  • Hypothalamic-pituitary dysfunction (Group 2)
  • Ovarian failure (Group 3)
  • Hyperprolactinaemia (Group 4)
  • Outflow tract defect (Group 5)

Fortunately not all causes of irregular periods are serious or permanent. Some of these are even normal such as age (i.e. puberty and menopause) or being pregnant.

Diagnosis of Irregular Periods

It is recommended to see your Doctor about irregular periods if:

  • You are under 45 and your periods suddenly become irregular.
  • Your cycles are less than 22 days or more than 35 days.
  • Your periods last longer than 7 days.
  • The difference between your shortest and longest cycle is 20 days or greater.
  • You have irregular periods and are struggling to get pregnant.

This does not automatically mean something is wrong, however it is recommended to go for a check up and make sure everything is normal.
Source: NHS (UK)

After carrying out a full history and physical examination, and sending you away for some tests, the Doctor may diagnose your irregular periods as abnormal.

Treatment of Irregular Periods

A variety of treatments exist to treat irregular periods, depending on the WHO Group and exact cause. These treatments fall into 6 broad categories:

  • Lifestyle modification
  • Medication (or withdrawal)
  • Assisted Reproductive Technology
  • Surgery
  • Supplements
  • Environment


Treatment of Irregular Periods

Treatment of Irregular Periods

Treatment of irregular periods varies according to which WHO Group you fall into and the exact cause. Fortunately, almost all cases of irregular periods…. Read more

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