Amenorrhea means an absence of menstruation. The term also applies to people who have not started their period by the age of 16, which is called primary amenorrhea. Secondary amenorrhea occurs in people who have missed 3 months of periods.

This article explores possible reasons for an absence of menstruation. It also covers when to see a doctor and the treatment options.

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Amenorrhea is an absence of menstrual bleeding.

A period, or menstrual bleeding, is the womb lining exiting the body. Amenorrhea is the absence of menstrual bleeding.

During the menstrual cycle, hormones cause an ovary to produce and release an egg. The ovary also releases the hormones estrogen and progesterone.

Estrogen primarily causes the womb lining to thicken, while progesterone prepares the womb for the implantation of an egg.

If no sperm fertilizes the egg, pregnancy does not occur, and the egg dissolves. The levels of estrogen and progesterone decline, and the womb lining falls away. It leaves the body through the vagina, giving the person a period.

If a female reaches the age of 16 without any periods, this is called primary amenorrhea.

Sometimes a person will have no menstrual bleeding for more than three cycles despite having had regular periods until then. If there is no natural cause for this, such as pregnancy, they have secondary amenorrhea. Secondary amenorrhea occurs in approximately 3–5 percent of adult women.

Natural causes of amenorrhea include pregnancy, breastfeeding, and menopause. In these cases, there is no need to see a doctor.

When a person has regular menstrual bleeding, this means that the ovaries, uterus, hypothalamus, and pituitary gland are working well.

The absence of menstruation can indicate a problem with one of these parts of the body, or there may be an abnormality of the genital tract. Lifestyle factors, an underlying health condition, and some medications can also cause amenorrhea.

Possible causes of an absence of menstruation include:

1. Birth control

Some birth control pills may cause missed periods or the complete absence of menstruation.

This can occur in the first few months of taking a new pill or if a person does not take any placebo pills or have a pill-free week each month.

Some of the other birth control methods, such as the hormonal intrauterine device (IUD), implant, and injection can also result in amenorrhea.

2. Nutritional deficiencies

Malnutrition may affect how the hypothalamus and pituitary gland function, which can lead to amenorrhea.

3. Low body weight

Having a low body weight can also prevent the hypothalamus and pituitary gland from functioning correctly. This can lead to a type of amenorrhea known as functional hypothalamic amenorrhea.

4. Stress

Stress can affect hormone levels in the body, and it is another cause of functional hypothalamic amenorrhea. People with this type of amenorrhea also have higher rates of depression and anxiety.

5. Excessive exercise

Excessive exercise is the third cause of functional hypothalamic amenorrhea. Some research estimates that half of the women who exercise regularly experience minor menstrual disorders.

6. Eating disorders

Having an eating disorder, such as anorexia or bulimia, may cause a person's periods to stop. This absence of menstruation is usually due to a nutritional deficiency or very low body weight.

7. Excessive weight gain

Rapidly gaining weight can cause a hormonal imbalance, which can lead to temporary amenorrhea.

8. Mental health medications

Some antidepressants and mood stabilizers may affect how the hypothalamus and pituitary gland work. If they are not producing the right levels of hormones, a person's periods may stop.

9. Polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a hormonal disorder that affects 6–8 percent of women worldwide.

PCOS causes a range of symptoms including:

PCOS may also lead to hyperandrogenemia, which is when a female has high levels of male hormones. A 2017 study of 266 women with PCOS found that over 78 percent of them had hyperandrogenemia.

Hyperandrogenemia may affect menstrual cycles and lead to amenorrhea.

10. Premature ovarian failure

Premature ovarian failure is when the ovaries stop working correctly before the age of 40.

This condition may lead to missed periods. However, it is not the same as early menopause, which is when menstruation stops completely.

11. Turner syndrome

Turner syndrome is a genetic disorder. People with this condition may have underdeveloped ovaries and an absence of menstruation.

12. Genital tract defects

Genital tract defects are structural problems that can cause an absence of menstruation or make it difficult for the menstrual blood to exit the vagina.

The most common female genital tract defect is an imperforate hymen, which is a hymen with no opening that closes off the vagina and does not allow blood to leave it during a period.

13. Pituitary gland problems

The pituitary gland releases the hormones that control the menstrual cycle. Issues with the pituitary gland, including those below, may lead to amenorrhea:

  • a pituitary gland tumor
  • postpartum necrosis, which is the premature death of cells in the pituitary gland after pregnancy
  • sarcoidosis, which is an inflammatory condition

Radiation therapy may also affect cells in the pituitary gland and cause amenorrhea.

People who miss three periods in a row but are not pregnant or likely to be entering menopause should see a doctor. This is especially important if they are experiencing additional symptoms.

People who have not started menstruating by the age of 16 should also speak to a doctor.

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Yoga, mindfulness, and meditation can help to manage stress.

A doctor will recommend the best course of treatment for amenorrhea after diagnosing its underlying cause.

Primary amenorrhea is often due to late puberty, which usually resolves over time. However, a doctor can help determine if there is another underlying cause for periods not beginning. If a hormonal imbalance is responsible, the doctor may prescribe hormonal therapy.

The causes of functional hypothalamic amenorrhea may require lifestyle changes:

  • Low body weight: A doctor may refer an underweight person to a nutritionist who can help them adjust their diet to reach a healthy weight.
  • Stress: Finding ways to manage stress, such as yoga, mindfulness, meditation, or seeing a therapist, may be beneficial.
  • Excessive exercise: The doctor may recommend a moderate exercise regime.

If a person has amenorrhea due to rapid weight gain, the doctor is likely to recommend a calorie-controlled diet and exercise.

In cases where amenorrhea develops due to a structural problem, surgery and an individualized treatment plan may be necessary.

Most causes of absence of menstruation are treatable. Following the treatment plan that a doctor recommends can help many people with amenorrhea regain a regular menstrual cycle.