Absent Periods (Amenorrhoea)

What is menstruation?

Menstruation, or having periods, is part of the female reproductive cycle.

While the average interval between periods is 28 days, many women will have cycles that are either longer or shorter than this.

During a period, the lining of the womb, which is no longer required if a pregnancy has not occurred, is shed and bleeding occurs through the vagina. This bleeding usually lasts between three and seven days.

What is amenorrhoea?

Amenorrhoea is the absence of menstrual periods. There are two main types of amenorrhoea:

  • Primary amenorrhoea: If a girl has not had her first period by the time she is 16, this is known as primary amenorrhoea.
  • Secondary amenorrhoea: This is when a woman, who has menstruated normally in the past, temporarily or permanently stops having periods.

While many women skip an occasional period for different reasons, amenorrhoea is diagnosed if the woman has missed three or more periods in a row.

What causes primary amenorrhoea?

The main cause of primary amenorrhoea is a delay in the beginning of puberty. While the delay is often not due to any disorder, there may be a number of reasons:

  • Hormonal imbalance.
  • Eating disorders such as anorexia nervosa and bulimia.
  • Intense physical athletic training which occurred before puberty.
  • Extreme obesity.
  • Some drugs may cause primary amenorrhoea, such as certain antidepressants.
  • Chronic illness.
  • Turner's Syndrome: This is when a woman is born with only one X chromosome (there should be two). Turner's Syndrome results in the woman having no ovaries, therefore menstruation cannot take place.

What causes secondary amenorrhoea?

  • The most common cause of secondary amenorrhoea is pregnancy. Periods may also stop temporarily after stopping the oral contraceptive pill. Periods usually return within eight or 10 weeks but may not return for a year or longer in some cases.

Other causes of secondary amenorrhoea include:

  • Stress: In some women, stress can cause amenorrhoea.
  • A problem with the ovaries: Ovarian disorders such as polycystic ovaries or an ovarian tumour can cause amenorrhoea.

Some of the conditions that cause primary amenorrhoea can also cause secondary amenorrhoea. These include:

  • Hormonal problems
  • Rapid weight loss often caused by an eating disorder.
  • Strenuous physical activity.
  • The use of certain drugs such as some antidepressants.

The absence of periods becomes permanent after the menopause or a hysterectomy.

How is amenorrhoea treated?

Primary amenorrhoea may not require any treatment. While it is necessary to investigate the cause of the condition, it may not warrant treatment, for example starting your period late may simply be hereditary.

If the underlying condition that is causing the amenorrhoea is treatable, then it should be treated.

With secondary amenorrhoea, the most important thing to do first is establish if the woman is pregnant.

If the amenorrhoea is caused by something else, treatment of that condition should be carried out where possible. For example, if a woman is obese, weight loss may bring about a return of her periods.

Can amenorrhoea cause infertility?

Generally, a woman who is not having periods is not ovulating, and therefore cannot become pregnant. In many cases, identification and treatment of the cause will allow the woman to become pregnant. There are some conditions where treatment may not be successful in restoring fertility.

If the condition is caused by something like stress, the amenorrhoea may pass when the stress passes. If you are worried about fertility and wish to become pregnant, you should visit your doctor for advice and investigation.

If a woman with amenorrhoea wishes to become pregnant and the cause is a disorder of the endocrine system, ovulation can often be induced by treatment with medications.

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