Polycystic ovary syndrome (PCOS) is not a disease in the usual sense; rather, it is a collection of symptoms that can affect a woman's reproductive health and heart health, and it can have other significant effects on health and lifestyle.
It affects 5% to 10% of women in their reproductive years. Its risk factors are not well known, but heredity does play a role.
The causes of PCOS are unknown. Researchers believe that insulin resistance and an imbalance of male hormones (e.g., testosterone) and female hormones (e.g., estrogens and progestins, those important for the menstrual cycle) contribute to the development of this condition.