Polycystic ovaries (PCO) are very common, affecting around 20 per cent of women. Polycystic ovary syndrome (PCOS) is also very common, affecting 5–10 per cent of women.

The term polycystic ovaries describes ovaries that contain many small cysts (about twice as many as in normal ovaries), usually no bigger than 8 millimetres each, located just below the surface of the ovaries. These cysts are egg-containing follicles that have not developed properly due to a number of hormonal abnormalities.

Polycystic ovary syndrome is the name given to a condition in which women with polycystic ovaries also have one or more additional symptoms. It was first ‘discovered’ in 1935 by Doctors Stein and Leventhal, so for many years it was known as the Stein-Leventhal syndrome.

Symptoms can include:

• irregular periods, or a complete lack of periods
• irregular ovulation, or no ovulation at all
• reduced fertility – difficulty becoming pregnant
• unwanted facial or body hair (hirsutism)
• oily skin, acne
• thinning hair or hair loss from the scalp (alopecia)
• weight problems – being overweight, rapid weight gain, difficulty losing weight
• depression and mood changes

PCOS affects women in different ways, so not all women will have all these symptoms. Some women may have only mild symptoms, while others may have a wider range of more severe symptoms. Symptoms usually start in adolescence, although some women do not develop them until their early to mid twenties.

Women with PCOS who have insulin resistance have an increased risk of developing a type of diabetes known as non-insulin-dependent diabetes (type 2 diabetes). This is much more likely to occur in women who are overweight, but can sometimes occur in women of normal weight too.

Women with insulin resistance may also be at risk of developing heart disease in later life. However, although risk factors for heart disease may be increased with PCOS, there is, as yet, no clear evidence that heart attacks are more common in women with the condition than in those who do not have PCOS. These risks can be reduced to a large extent by preventive measures such as good nutrition and exercise. Preventive measures are particularly important for women who are very overweight, and for women who have a family history of diabetes or heart disease.