Causes of absent periods 

It's normal for your periods to stop at certain points, although absent periods are sometimes the result of an underlying health problem.

In some cases a cause may not be found.

Naturally absent periods

It's normal for periods to stop while you're pregnant or breastfeeding, and they often become less frequent during the menopause, when the ovaries stop regularly producing eggs, usually at around the age of 50.

Becoming pregnant without realising is a surprisingly common cause of an absent period. This often happens when your method of contraception fails without you realising.

In the case of pregnancy and breastfeeding, your periods will eventually return. After the menopause you'll stop having periods altogether.

Developmental delays

Girls often start having periods from around the age of 12. However, some girls don't have their first period until later, particularly if this was the case with their mother or older sisters.

A delay in starting monthly periods is usually nothing to worry about. Most girls will eventually start having periods by the time they're 16 to 18 years old.

Contraception

Some women who use a contraceptive implant, such as a hormonal coil, a contraceptive injection or, less commonly, the contraceptive pill – sometimes called the mini pill – may find their periods become irregular or stop completely.

Your periods should start again after you stop using these forms of contraception, although occasionally these effects can persist.

Visit your GP for advice if you haven't been using these types of contraception for six months or more and you still haven't had your period.

Medical conditions

Medical conditions can also cause absent periods. Depending on when the condition develops, it can mean a girl's periods don't start by the expected age (primary amenorrhoea), or a girl or woman who's previously had periods stops having them (secondary amenorrhoea).

Some of the main medical conditions that can cause absent periods are described below.

Polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common condition responsible for as many as one in three cases of absent periods.

The features of PCOS include:

  • a number of under-developed egg sacs (follicles) in your ovaries
  • the ovaries not regularly releasing eggs (ovulation)
  • having high levels of male hormones (androgens) in your body

As well as causing absent periods, other symptoms of PCOS include excessive body hair, problems getting pregnant and weight gain.

Hypothalamic amenorrhoea

The menstrual cycle is regulated by a part of the brain known as the hypothalamus. It produces hormones that cause the ovaries to release eggs. In cases of hypothalamic amenorrhoea, the hypothalamus stops producing these hormones and the menstrual cycle stops.

It's unclear exactly why the hypothalamus stops producing these hormones, but it's been linked to:

  • excessive weight loss – for example, as the result of an eating disorder such as anorexia nervosa
  • excessive exercise
  • stress
  • long-term (chronic) illnesses – such as heart disease or uncontrolled diabetes

Hypothalamic amenorrhoea is more common in women whose profession requires a combination of physical fitness and maintaining a low body weight, such as athletes and dancers.

Even if you're unconcerned about not having a period, you should still seek medical advice if you think you have hypothalamic amenorrhoea as it can lead to brittle bones (osteoporosis) and put you at risk of bone fracture.

Hyperprolactinaemia

Hyperprolactinaemia is where you have excessively high levels of a hormone called prolactin in your body.

High levels of prolactin are normally only needed after giving birth, as they help stimulate the production of breast milk. Having high levels at other times can disrupt the normal menstrual cycle and lead to absent periods.

Hyperprolactinaemia is thought to affect around 1 in every 200 women. It can have a wide range of causes, such as:

Hyperprolactinaemia can also occur as a side effect of treatments and medications, such as:

Women who regularly use heroin also often develop hyperprolactinaemia.

Premature ovarian failure

Premature ovarian failure is where the ovaries stop producing eggs in women who should still be young enough to ovulate (usually 45 or younger).

It's estimated premature ovarian failure affects 1 in every 100 women before the age of 40, and 1 in every 20 women before the age of 45.

Many cases of premature ovarian failure are thought to be caused by the immune system malfunctioning and attacking the ovaries. The condition has also been linked to having chemotherapy or radiotherapy.

Seek medical advice if you think you have premature ovarian failure, even if you're not concerned about having periods. If you have the condition, your risk of developing osteoporosis and heart disease is increased.

Thyroid conditions

The thyroid gland is found in the neck. It produces hormones that are released into the bloodstream to control the body's growth and metabolism. They affect processes such as heart rate and body temperature, and help convert food into energy to keep the body going.

In some women the thyroid gland produces too much thyroid hormone. This is known as having an overactive thyroid gland, or hyperthyroidism.

In other women the thyroid gland produces too little thyroid hormone. This is known as having an underactive thyroid gland, or hypothyroidism.

Both hyperthyroidism and hypothyroidism can cause absent periods.

Genetic conditions

Although uncommon, absent periods can also be caused by a number of conditions resulting from genetic problems. These include:

  • Turner syndrome – affecting around 1 in every 2,000 girls, Turner syndrome causes girls to be born with ovaries that don't produce the hormones needed to trigger the menstrual cycle
  • Kallmann syndrome – a rare syndrome that affects around 1 in every 10,000 births, where hormones that normally trigger sexual development are missing
  • androgen insensitivity syndrome – an even rarer syndrome, affecting around 1 in every 20,000 births, where a child is genetically male but their genitals appear to be female

Birth defects

In rare cases absent periods may be caused by a problem to do with the development of a girl's reproductive system that's been present from birth, such as having no womb or vagina.

Page last reviewed: 06/10/2015

Next review due: 06/10/2017