The exact cause of PCOS is unknown, however there appears to be a connection with a woman's genetics (i.e. hereditary, passed down through the family), insulin resistance and her lifestyle or environment.

Genetics

Immediate female relatives of women with PCOS (i.e. daughters/sisters) have up to a 50 per cent chance of having the condition. Diabetes is also a common feature in families of those with PCOS. The exact genetic components that could lead to PCOS have not yet been identified, it is likely to be complex and involve multiple genes that control:

a)  Insulin regulation

b)  Male hormone production, or

c)  The hormones involved in regulating ovulation and menstruation

Insulin resistance and lifestyle factors

Insulin resistance is present in up to 80 per cent of women with PCOS.  Insulin resistance is a state where the body cannot carry out the complex normal actions of insulin. Insulin resistance can contribute to an increased risk of developing type 2 diabetes and cardiovascular disease.

Insulin has a range of other functions in the body in addition to regulating blood glucose levels. In PCOS, high levels of insulin can increase the production of male hormones (androgens such as testosterone) in the ovary. Both high insulin and male hormones contribute to symptoms such as irregular periods, difficulty in ovulating, excessive hair growth and acne.

Insulin resistance is caused in part by lifestyle factors including being overweight due to poor diet or physical inactivity.

Women with PCOS are more likely to have a particular form of insulin resistance due to genetic factors that is separate from the insulin resistance associated with being overweight. This means that women with PCOS can have:

• A genetic predisposition to having insulin resistance
• Insulin resistance due to lifestyle factors, or
• A combination of both of these factors

Weight

Being above your most healthy weight worsens insulin resistance and the existing symptoms of PCOS. Some women with PCOS report that when they are a normal weight they don't show symptoms such as menstrual irregularity or excessive hair growth and that these symptoms only appear once they gain weight. The symptoms of PCOS can therefore be reduced if a healthy lifestyle is implemented.

Up to 10 per cent of women of reproductive age have PCOS. This increases to up to 30 per cent in overweight women. The number of women who are above their most healthy weight is increasing in today's society. This means that as more people are above a healthy weight in the future, the prevalence of PCOS is also likely to increase. Therefore, a healthy lifestyle and weight management is important not only in treating PCOS, but also in preventing it.

Content Updated June 06, 2008