Absent Period (Amenorrhea)

Menstrual cycle disorders can cause a woman’s periods to be absent or infrequent. Although some women do not mind missing their menstrual period, these changes should always be discussed with a health care provider because they can signal underlying medical conditions and potentially have long-term health consequences. A woman who misses more than three menstrual periods (either consecutively or over the course of a year) should see a health care provider.

Amenorrhea — Amenorrhea refers to the absence of menstrual periods, and is classified as either:

Primary (when menstrual periods have not started by age 15 years)

Secondary (when menstrual periods are absent for more than three to six months in a woman who previously had periods)

Oligomenorrhea — Oligomenorrhea is the medical term for infrequent menstrual periods (fewer than six to eight periods per year).

There are certain times when it is normal not to have periods. These include:

  • Before puberty. Girls start to develop from around the age of 9 and their periods start a year or two later. Up until that point girls do not have periods.
  • During pregnancy. If you are pregnant, your periods will normally stop until after the baby is born.
  • During breast-feeding. If you are fully breast-feeding, you will normally not have a period until you stop. You may find you have a bleed if you drop a feed, or start to breast-feed much less.
  • After menopause. The menopause is the time in your life when your ovaries stop producing eggs and you stop having periods. The average menopause is around the age of 51.
  • If you are using certain types of contraception. Some types of contraception may stop periods. They do not do so in all women; however, it is normal not to have periods (or to have very light periods) if you are using:
    • The progestogen-only contraceptive pill (POCP, or mini pill).
    • A certain type of coil, called the intrauterine system (IUS).
    • A progestogen contraceptive injection.

Some causes of absent periods are discussed below.


Stress affects the chemical messengers called hormones which are released from your brain. These hormones then go on to affect other hormones released from your ovaries which normally trigger your periods. Stress or a sudden shock can stop your periods in this way. Usually if this is the case, they resume naturally over some time.

Low body weight

Losing weight may result in periods stopping. This can occur if your body mass index (BMI) goes below 19. If you have an eating disorder called anorexia nervosa, losing too much weight can result in your periods stopping. It may also happen to athletes, gymnasts, long-distance runners and people who do an excessive amount of exercise.

Polycystic ovary syndrome (PCOS)

PCOS is a common condition which can cause periods to be very infrequent or sometimes stop altogether. Women with PCOS may have other symptoms such as difficulty losing weight, spots (acne) and too much body hair.

Hormone problems

A number of conditions which affect hormone levels may cause periods to stop. This includes:

  • A condition where a hormone called prolactin is too high. This is called hyperprolactinaemia. The most common cause of this is a non-cancerous (benign) growth in the brain.
  • Conditions affecting a gland in your neck called the thyroid gland. The thyroid gland produces hormones which may affect periods. If you are producing either too much hormone (hyperthyroidism) or too little (hypothyroidism), your periods may be affected.
  • Congenital adrenal hyperplasia. This is a rare inherited condition where steroid hormones of the adrenal glands are not produced normally. There are different forms of this condition but some can lead to absent or infrequent periods.
  • Another disorder of the steroid hormones, called Cushing’s syndrome.

Inherited problems

In rare cases, abnormal genes can be a cause of not having periods. In most of these, there will be primary amenorrhoea, ie periods never start. One example of this is Turner syndrome. In this condition, girls tend to be short, have particular features and have ovaries which do not work properly. They often do not start periods when other girls of their age do.

Other inherited (genetic) conditions may cause differences in genitals and female organs. For example, in a condition called androgen resistance syndrome, the child has female genitals outside but no female organs on the inside. With no ovaries or womb (uterus), these children will not have periods.

Early menopause

The average time for women’s periods to stop is at the age of 51. However, there is quite a wide range. If periods stop before the age of 40, this is very early and is said to be premature menopause. Periods stop and there are usually other symptoms of menopause such as hot flushes.

Medicines and medical treatment

A number of contraceptive treatments can stop you having periods. Other medicines can affect periods too. Examples are some medicines for schizophrenia (antipsychotic medicines), an anti-sickness medicine called metoclopramide and strong painkillers called opiates.