The UCSF National Center of Excellence in Women's Health

Polycystic Ovarian Syndrome (PCOS) is one of the most common disorders of the endocrine system affecting women of reproductive age. The endocrine system regulates and secretes hormones throughout the body. Thus, PCOS is often associated with hormone irregularities. The exact cause of PCOS is unknown. It may be due to a combination of several factors, including insulin resistance, obesity, and changes in hormone production. PCOS is considered a syndrome because the signs and symptoms vary from woman to woman.

With PCOS, the body produces higher levels of androgen, or “male” hormones. These high levels of androgens prevent the ovaries from making enough of progesterone, which is necessary for a normal menstrual cycle. Estrogen hormone levels are usually normal. The higher levels of androgens and lower levels of progesterone result in undeveloped egg follicles. Therefore, ovulation cannot occur and the immature follicles turn into small cysts in the ovaries.

How common is it?

PCOS affects approximately 5-10% of women who are of childbearing age and is the most common endocrine disorder among pre-menopausal women. However, about 30% of women have at least some characteristics of the syndrome.

What causes PCOS?

The exact cause of PCOS is unknown. However, researchers are currently looking for a genetic link among families. In addition, many current studies are focusing on insulin resistance as a potential cause of the syndrome. “Insulin resistance” describes the body's inability to utilize the hormone insulin efficiently. Present data suggests that elevated insulin levels may cause increased levels of androgens and worsening PCOS symptoms.

Who’s at risk?

There appears to be a hereditary component to PCOS, and women who have female relatives with PCOS may be at a higher risk for developing the syndrome themselves. Obese women can also be predisposed to PCOS. Women who are diabetic, have problems with their adrenal glands, thyroid gland, or pituitary gland can develop symptoms of PCOS, but may not have the syndrome. A woman with PCOS will usually develop symptoms within a few years of puberty, though sometimes the syndrome appears later in life.

Is there a cure?

There is currently no cure for PCOS; it is managed on a long-term basis. Most women are able to manage the syndrome through a healthy, well-balanced lifestyle.

Does it get worse over time?

Symptoms may worsen during a woman's prime reproductive years, ages 20-40. This is particularly seen in women who gain a significant amount of weight. However, as women near menopause, the severity of symptoms can subside.

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PCOS Common Questions

What is Polycystic Ovarian Syndrome?

How common is it?

What causes PCOS?

Who’s at risk?

Is there a cure?

Does it get worse over time?