How to get pregnant with Irregular periods

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female infertility treatment for women with irregular period trying to get pregnant

Interpreting test results
– Hypothalamic-pituitary failure
– Hypothalamic-pituitary dysfunction
– Ovarian failure
– Hyperprolactinaemia
– Outflow tract defect

Revised: 7/06/2021


Getting pregnant with irregular periods is a step-by-step process. The first step towards treatment is understanding and diagnosing the exact cause of your irregular periods.

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 range is slightly shorter in women aged 40-44, with regular cycles found to occur between 23-30 days.
Source: Munster K, et al. (1992)

It is not uncommon for a womans cycle to vary by a few days each time. However a large variation in blood loss during menstruation or duration of periods is also considered irregular. At the extreme end, menstruation can fail to occur in some women for at least 6 months, known as amenorrhea.

Ovulation disorders are very common and present in 18-25% of couples who see a specialist for infertility treatment. In the general population of women the proportion of normal, incomplete and anovulatory cycles also changes according to age.

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. Source: Johnson M H (2018)

Woman who have never had entirely normal cycles may be the result of some failure during maturation of the neuroendocrine system at puberty.

For reference women with normal cycles (aged under 35) have a cumulative conception rate of approximately 50% after 2 cycles, rising to 85% after 6 months 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. This intervention is not the same for every woman and depends on the findings by your Doctor or Specialist, following various tests, as to the most likely cause of your irregular periods.

Common signs of pregnancy when you have irregular periods

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 weeks of gestation.

A home pregnancy urine (hCG) test can generally confirm a positive pregnancy in women with irregular periods just 2 weeks after intercourse.

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

When to see a Doctor about irregular periods

According to NHS (UK) guidelines it is recommended to see your GP 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.


  • 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
    Source: Tsukahara Y, et al. (2021); Heather A K, et al. 2021; Ackerman K E, et al. (2015)
  • Impaired physical and sexual development, in long term cases beginning at puberty
    Source: Dynnik V, et al. (2020).
  • Premature death
    Source: Wang Y X, et al. (2020)


There are many causes of irregular periods and some of these may be normal.

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