Menopause is simply the name given to the last menstrual period, but for most women it means much more than this. It is the cycle in a woman’s life when her ovaries stop producing eggs, when her periods begin to stop and when her hormone levels change. Menopause is something that typically happens between the ages of 47 and 53. It means hot flushes, no more periods, an end to a woman’s reproductive years – and is a natural part of her life, which for a women in her teens, 20s, 30s and early 40s, should be far in the future.

Premature Ovarian Insufficiency

Premature menopause, premature ovarian failure and/or premature ovarian insufficiency (POI) are terms that are generally used to describe the same condition, whatever the cause. The words are often used interchangeably, which can be confusing at first. There is no internationally agreed wording, however the newer term for the condition is premature ovarian insufficiency, which may describe it more accurately as the ovaries may not have irreversibly ‘failed’ and premature ovarian insufficiency has important differences from the ‘normal’ menopause which occurs at an average age of 51-52 in the UK.


Age is the key factor, as early or premature menopause or POI is typically used to mean menopause that comes well before the average age of normal menopause — when you’re still in your teens, 20s, 30s, or early 40s. Early menopause is used to describe menopause before the age of 45 and POI when it occurs below the age of 40.

Simply put, it means that the ovaries aren’t working properly. They stop producing eggs years, and in some cases even decades, before they should. In addition, the ovaries are unable to produce the hormones estrogen and progesterone, which have important roles in women’s health and well-being.

POI is different to menopause that occurs at around the average age (52 years). Not only does it occur at a very young age, but the ovaries often don’t completely fail. This means that ovarian function can fluctuate over time, occasionally resulting in a period, ovulation or even pregnancy, several years after diagnosis. Because of this intermittent temporary return of ovarian function, approximately 5-10% of women with POI may still conceive.


How common is it?

Approximately one in every 100 women under the age of 40, one in 1,000 women under 30 and one in 10,000 under 20 experience POI. In Britain 110,000 women between the ages of 12 and 40 are affected. A spontaneous (natural) early menopause affects approximately 5% of the population before the age of 45.

Spontaneous POI affects one per cent of women before the age of 40, however increasing numbers of women are experiencing iatrogenic POI (POI caused by surgery or cancer treatments), therefore the exact number of women affected by all causes combined is unknown.

What causes POI?

POI can occur for several reasons. Unfortunately there is still a lot that we don’t understand about POI and in the majority of women (90%), no underlying cause will be found. This type of POI is usually called spontaneous or idiopathic POI. Not knowing why you have developed POI can make it harder to cope psychologically with the diagnosis, however it doesn’t affect the treatment you should be offered. Some of the causes which may be identified include:

Auto-immune disease

Auto-immune disorders are conditions in which the body’s immune system can attack its own tissues. If damage occurs to the ovaries it can result in POI. In around 5% of women with POI it is thought to occur due to auto-immune disease.

POI is connected with other auto-immune disorders including underactive thyroid, type 1 diabetes, and Addisons disease.

Genetic causes

Abnormalities in the female sex chromosome (the X chromosome) or other genes affecting sex hormone function can cause POI and many different genetic defects have been identified. The most common of these is Turner syndrome, where the one of the X chromosomes is missing.  POI is also associated with some rare conditions which tend to run in families such as Fragile X syndrome and galactosaemia.

Genetic causes are more common in women with a family history of POI and in women in whom POI is diagnosed at a very early age (e.g. in their teens or 20’s) and in women often who’s periods never start.


There have been reports of POI occurring after infections including mumps, tuberculosis and malaria, but this is extremely rare.


Surgical removal of the ovaries before the age of 40 is another form of POI. This sudden removal of ovarian hormones can often lead to an abrupt onset of menopause symptoms.  Removal of the ovaries (with or without hysterectomy) can be required for several reasons including ovarian cancer, ovarian cysts, endometriosis or severe premenstrual syndrome. Hopefully, this type of surgery will be planned in advance, so you would have the opportunity to discuss with your specialist about the option of starting hormone replacement at the time of or very shortly after surgery, to help minimise the menopausal symptoms.

Cancer Treatment

As well as surgery, other cancer treatments such as chemotherapy or radiotherapy can cause temporary or permanent damage to the ovaries, resulting in POI. The chances of this occurring depend on the chemotherapy drugs used, the site of radiotherapy and your age at the time of treatment.

Menopause terms explained

Menopause and Climacteric

The term menopause is often used incorrectly. As explained earlier, menopause means your last menstrual period. Climacteric more accurately describes the gradual changes and symptoms which occur as the production of hormones and ovarian function diminishes. The process whereby periods stop is a gradual one, in most cases, and is a long process of changes akin to puberty.


This is the stage where your periods are still regular but the first symptoms such as night sweats and mood swings may occur. However, sometimes it is used to mean the years of your life when your periods are regular and you are fertile. So make sure you know which meaning the word has in the context you are reading it or being told about it.


POI is not to be confused with perimenopause. Perimenopause lasts several years on either side of your last menstrual period. Vague symptoms you may not have connected may become significant when viewed as part of perimenopause. It is during this time that you notice the most physical changes, when your periods may become irregular and hot flushes and night sweats may start. During this stage you are still fertile and may conceive although the chances of getting pregnant are often negligible. Perimenopause is the time during which your ovarian hormones start to change and your egg production is significantly reduced. One of the key indicators of this change is the rise of the Follicle Stimulating Hormone levels – see below.


This term describes the time from after your last menstrual period to the end of your life



Estrogen is the principal female sex hormone produced by the ovaries and is vital for the growth of eggs and for the reproductive process. It is also plays a role throughout the body in maintaining cardiovascular, brain and bone health, along with many other tissues in the body.

Estrogen is not just one hormone but three:

Estradiol is the main type of estrogen and the most potent. It plays a major role during puberty. It both enlarges the womb and thickens its lining (endometrium). It is also used by the ovaries to signal to the hypothalamus and pituitary gland that the egg follicles have been stimulated and FSH (Follicle Stimulating Hormone) production slows down.  Eestrone is  produced by the adrenal glands and estrogen manufacturing fat cells. This type of estrogen continues to be produced after the menopause. Estriol is converted from estrodiol and estrone by the liver.



Progesterone is a female hormone produced by the ovaries. One of its many functions is to help to maintain pregnancy. It is secreted by the corpus luteum during the second half of the menstrual cycle and signals to the uterus that an egg has been released.


Follicle Stimulating Hormone

Follicle Stimulating Hormone (FSH) is released by the pituitary gland which is carried to the ovaries to stimulate the follicles. As FSH levels rise, some of the eggs respond with low levels of estradiol. By doing so the ovaries communicate back to the pituitary gland that the egg follicles have been stimulated and FSH production slows down.

However, when the supply of egg follicles is low and they are unresponsive to stimulation, the pituitary gland tries to compensate by producing more FSH every month. The overall levels of FSH rise.

POI is suspected if you are under 40, have had no periods, or infrequent periods, for some time and your FSH level is over 30 iu/l.

A single FSH level test with no menopausal symptoms is not conclusive as FSH levels can fluctuate. Levels should therefore be repeated in around 4-6 weeks to confirm the diagnosis.


Lutenizing Hormone (LH)

Lutenizing Hormone (LH) is released by the pituitary gland into the bloodstream and triggers ovulation i.e. the active follicle bursts and releases the egg. The ruptured follicle sac called the corpus luteum (body of yellow) turns yellow and, due to the action of the LH produces progesterone.  LH is also elevated in POI, but usually to a lesser extent than FSH.



Although it is often thought of as a male hormone, testosterone is also very important in women. It plays a role in libido and sexual health, bone strength and energy. Approximately half of our testosterone is produced by the ovaries and the other half from the adrenal gland. Testosterone levels fall gradually with age but can drop by 50% if the ovaries are removed surgically. Women with POI have been shown to have lower levels of testosterone compared to other women their age.