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What is oligomenorrhea?

Oligomenorrhea is medical terminology for late irregular menstrual periods – when menstruation occurring at greater than 35 day cycles (once every 35 days or longer). In most cases oligomenorrhea caused by anovulation triggered by hormonal dysfunctions such as Polycystic Ovarian Syndrome, hyperprolactinemia, Cushing’s syndrome, hormonal medications, etc. But sometimes stress, poor nutrition, excessive exercises and anabolic steroid drugs (for athletic performances) also cause oliogomenorrhea.

Women with normal menstrual cycle usually have periods 11-12 times a year but women with late irregular periods menstruate only 4-9 times a year.

Late periods are just a symptom of several diseases and health conditions and the diagnosis sometimes could be pretty complicated. In all cases oligomenorrhea is a result of hormonal dysfunctions.

Numerous conditions can cause oligomenorrhea, ranging from lifestyle circumstances to serious medical issues.

Oligomenorrhea symptoms

Most common symptoms of oligomenorrhea include the following:

  • Long menstrual cycle (more than 35 days but less than 6 months) – menstrual periods occurs at intervals of greater than 35 days;
  • Four to nine menstrual periods in a year;
  • Infertility (as a result of long menstrual cycles without ovulation);
  • Osteoporosis and cardiovascular disease (as a result of hormone deficits);
  • Irregular menstrual periods with unpredictable flow (sometimes very poor/scanty and sometimes menstrual bleeding).

Here we introduce the most common causes of oligomenorrhea.

Oligomenorrhea causes

Polycystic Ovary Syndrome

Women with polycystic ovary syndrome (PCOS) are also likely experience oligomenorrhea because of ovarian dysfunction – inappropriate levels of both female and male hormones. During PCOS ovaries are filled with small cysts (polycystic) which are causing anovulation (absence of ovulation) and late periods.

Women with PCOS show menstrual irregularities that range from oligomenorrhea and amenorrhea to very heavy and irregular periods.


Oligomenorrhea that occurs in adolescents is often caused by immaturity or lack of synchronization in hypothalamo-pituitary-ovarian system. Very often teenage girls experience oligomenorrhea associated with immature hormonal function.  In most cases it is just a temporary oligomenorrhea which followed by regular menstrual cycles by 14-15.

Female Athlete Triad

Female Athlete Triad is a syndrome in which eating disorders (or low energy availability), amenorrhoea or oligomenorrhoea and decreased bone mineral density (osteoporosis and osteopenia) are present.  This syndrome also known as “Triad” – this condition is seen in females participating in sports that emphasize leanness or low body weight. The Triad is a serious illness with lifelong health consequences and can potentially be fatal.

Adrenal hyperplasia

Adrenal hyperplasia is characterized by increased levels of androgens which trigger oligomenorrhea, clitoral enlargement and male distribution of hair, fat, and muscle mass.


Main reason of hyperprolactinemia could be prolactin-secreting pituitary tumor and oligomenorrhea and/or amenorrhea could be the first signal of hyperprolactinemia. Women with hyperprolactinemia could mention also galactorrhea, infertility, loss of libido and sparse pubic hair. A headache and visual field disturbances such as diminished peripheral vision, blurred vision, diplopia, and hemianopia could be a sign for tumor expansion.

What is oligomenorrhea ?


Menstrual cycle can be disturbed also because of stress – emotional or physical stress. In both cases hormonal dysfunctions are noted. Changes in female hormones can be a reason for oligomenorrhea.

Eating disorders (bulimia, anorexia)

Oligomenorrhea can be noted in women with dramatic change of weight – more than 20% of ideal body weight (BMI should be checked). Anorexia could cause irregular late periods or even amenorrhea (absence of periods for more than 6 months). During anorexia girls could display dramatic skeletal muscle atrophy, loss of fatty tissue, dry or sparse scalp hair, lanugo on the face and body and dry skin. Common are also constipation, decreased libido and sleep disorders.

In these cases the oligomenorrhea occurs because body fat drops too low compared to weight. Emotional stress related to performance anxiety may also be a factor of irregular late periods in these women.

Diabetes mellitus

Irregular late periods could be very early sign of diabetes mellitus. Generally speaking, menstrual dysfunctions are very common in women with diabetes. Besides irregular late periods, diaberic women could have  excessive hunger, polydipsia, polyuria, weakness, fatigue, dry mucous membranes, poor skin turgor, irritability and emotional lability and weight loss.


It is well know that thyroid dysfunctions could trigger menstrual dysfunctions. Besides irregular late periods, hypothyroidism may result in fatigue; forgetfulness; cold intolerance; unexplained weight gain; constipation; bradycardia; decreased mental acuity; dry, flaky, inelastic skin; puffy face, hands, and feet; hoarseness; periorbital edema; ptosis; dry, sparse hair; and thick, brittle nails.


Hyperthyroidism is the term for overactive tissue within the thyroid gland causing an overproduction of thyroid hormones which is always provoking problems in menstrual cycle. Thyrotoxicosis could trigger irregular late periods along with reduced fertility. Cardinal findings include irritability, weight loss despite increased appetite, dyspnea, tachycardia, palpitations, diarrhea, tremors, diaphoresis, heat intolerance, an enlarged thyroid and, possibly, exophthalmos.


Perimenopause is a special period of women life – period of hormonal changes – mainly decreased levels of female hormones responsible for irregular late periods and following amenorrhea (typical for menopause).


Medical drugs that increase androgen levels — such as corticosteroids, corticotropin, anabolic steroids, danocrine, injectable and implanted hormonal contraceptives — could cause oligomenorrhea. Irregular late periods can be temporary and normal periods can be resumed after stopping of mentioned drugs. Other drugs that may cause oligomenorrhea include phenothiazine derivatives and amphetamines, and antihypertensive drugs, which increase prolactin levels.

Chronic diseases

Serious general diseases always change hormonal and immune systems and could trigger hormonal dysfunctions. The main reason of irregular late periods during chronic illnesses is disturbed interactions between hypothalamus, pituitary gland and ovaries.

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