Causes of PCOS and Common Risk Factors
Women's HealthReproductive System Disorders

Understanding What Causes Polycystic Ovary Syndrome (PCOS): Key Factors You Should Know

Understanding What Causes Polycystic Ovary Syndrome (PCOS): Key Factors You Should Know
Canva (3); Everyday Health
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Updated on December 3, 2024
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Polycystic ovary syndrome (PCOS) is a hormonal disorder that can affect females of reproductive age. This disorder commonly causes symptoms such as irregular periods, increased body hair, acne, hair thinning, weight gain, and infertility. Up to 13 percent of reproductive-age women have PCOS,

 making it the most common hormonal disorder in this group.

Researchers don’t know exactly what causes PCOS, but some key factors, like genes, stress, and hormones, may play a role. Here’s what research says about the potential causes of PCOS.

Genetics

PCOS is a highly heritable condition, which means that it runs in families and has a strong genetic component. So far, researchers have found 19 genes that are strongly associated with PCOS.

A genetic predisposition doesn’t necessarily mean you’ll develop the condition. Some research has found that even among identical twins, who have the same genes, one sibling may develop PCOS while the other does not. With this finding, it’s possible that genes are only a piece of the puzzle. You may also need exposure to other factors that can “trigger” the genes’ expression to develop PCOS.

Hormonal Imbalances

An imbalance of sex hormones also seems to contribute. People with PCOS commonly have higher levels of male sex hormones, called androgens. Higher levels of male sex hormones may contribute to the symptoms of PCOS by:

Disrupting ovulation, which can cause you to have irregular periods or no periods at all
  • Stopping the ovarian follicles (which typically hold immature eggs) from developing normally and being ovulated
  • Causing excessive hair growth on the face or body and hair loss on the scalp
  • Causing acne

Insulin Resistance

Another hormone that may be involved in PCOS is insulin. Insulin helps the body’s cells take up glucose from the blood and use it as energy. In some people, the cells have an increased tolerance to insulin, so they don’t respond to the hormone as well as they should. This condition is called insulin resistance, and about 50–90 percent of people with PCOS have it.

With insulin resistance, blood glucose levels go up, which makes the body produce more and more insulin as it tries to compensate for the high blood glucose.

 When insulin levels are high, and a person has insulin resistance, androgens also rise. This is because insulin suppresses the production of a protein that binds to androgens and other sex hormones, leaving more free androgens available.

 Higher androgen levels, in turn, may cause more symptoms of PCOS.

Insulin resistance also commonly causes weight gain, which can also worsen insulin resistance.

 And too-high levels of insulin in the body can affect your periods, as well. High insulin levels may suppress follicle stimulating hormone (FSH), which is needed for the follicle to mature before ovulation.

 Excess insulin may also change how your ovaries respond to luteinizing hormone, which the body releases to help signal and trigger ovulation.

Inflammation

Some evidence suggests that chronic inflammation may play a role in PCOS.

Typically, inflammation is the result of your immune system responding to injury or illness. Chronic, or long-lasting, inflammation may be caused by obesity, insulin resistance, or other conditions.

Some researchers also believe that increased inflammation in the body can cause insulin resistance, which in turn causes excessive levels of male hormones, leading to PCOS.

 Inflammation can also affect how well the ovaries function, stopping the follicles from evolving normally and leading to PCOS.

Obesity

Obesity is common among people with PCOS, affecting 38–88 percent of those with the disorder.

The link between obesity and PCOS is complex. While it isn’t entirely clear which one causes the other, the two are very closely linked: Obesity seems to increase PCOS risk, and vice versa.

One of the possible explanations for this link is that the male sex hormones that are elevated in PCOS can cause your body to produce more fat cells around the tummy, which can contribute to weight gain and obesity.

 Then, obesity causes inflammation, which may contribute to PCOS.

Insulin resistance also plays a role. It’s more difficult to lose weight or maintain a healthy weight with insulin resistance, which is commonly associated with PCOS. And in turn, excess fat causes your body to produce more insulin.

A strong genetic component to obesity may be at play here, too. Studies suggest that genes associated with fat mass and obesity are involved in PCOS. It may be the case that people with a genetic predisposition towards obesity are also more prone to PCOS.

Either way, reducing obesity and overweight may go a long way in preventing and managing PCOS, with even modest weight loss leading to symptom improvement in some research.

 If you’re looking to lose weight, you can talk to your doctor for their guidance on diet, exercise, and medication.

Stress

Stress and anxiety can contribute to PCOS by raising levels of cortisol, the body’s stress hormone. People with PCOS tend to have higher stress levels, research suggests.

 High cortisol levels from heightened stress may make it harder for your body to use insulin, which may worsen PCOS.

Some other conditions can mimic PCOS in terms of high cortisol levels. These include Cushing’s syndrome and hypothyroidism, which your doctor will likely rule out before diagnosing PCOS.

To help manage your PCOS after diagnosis, try to prioritize rest, relaxation, and other strategies for stress relief.

The Takeaway

  • PCOS is a complex condition with many intertwined factors.
  • Genes, inflammation, obesity, insulin resistance, hormonal imbalances, and even stress can all affect a person’s risk of developing PCOS.
  • Personalized, holistic approaches that consider not just a person’s biology but also their lifestyle and mental health are important for treatment and prevention.

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Anna L. Goldman, MD

Medical Reviewer
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Anna L. Goldman, MD, is a board-certified endocrinologist. She teaches first year medical students at Harvard Medical School and practices general endocrinology in Boston.

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Ana Sandoiu, MA

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Ana Sandoiu is a freelance medical copywriter, editor, and health journalist with a decade of experience in content creation. She loves to dive deep into the research and emerge wi...

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