Understanding What Causes PMOS (Formerly Known as PCOS): Key Factors You Should Know
Updated on July 8, 2026
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Editor’s Note: In May 2026, the Endocrine Society and other international experts officially renamed polycystic ovary syndrome (PCOS) polyendocrine metabolic ovarian syndrome (PMOS). This change better reflects the condition’s nature as a systemic metabolic disorder. This article has been updated to reflect the new terminology.
Polyendocrine metabolic ovarian syndrome (PMOS), formerly known as polycystic ovary syndrome (PCOS), is a hormonal disorder that affects up to 13 percent of women of reproductive age. This disorder commonly causes symptoms such as irregular periods, increased facial and body hair, acne, scalp hair thinning, weight gain, and infertility.
Researchers don’t know exactly what causes PMOS, but some key factors, like genes, stress, and hormones, may play a role. Here’s what research says about the potential causes of PMOS.
Genetics
PMOS is a highly heritable condition, which means that it runs in families. In fact, most cases are genetic. So far, researchers have found 19 genes that are strongly associated with PMOS.
A genetic predisposition doesn’t necessarily mean you’ll develop the condition though. Environmental and other risk factors, such as poor diet, stress, and diabetes, may also play a role.
Researchers have called for more large-scale studies to better understand how genetic and environmental factors may interact to influence the development of PMOS.
Hormonal Imbalances
An imbalance of sex hormones also seems to contribute to the development of PMOS. Women with PMOS commonly have higher levels of male sex hormones, called androgens.
Hyperactive gonadotropin-releasing neurons from the hypothalamus lead to the release of more luteinizing hormone (which stimulates the ovaries to produce excess testosterone) and less follicle-stimulating hormone, which results in an excess production of androgens and blocks normal ovulation.
Excess androgens may:
- Disrupt ovulation, which can cause irregular periods or no periods at all
- Stop the ovarian follicles (which typically hold immature eggs) from developing normally
- Cause extra hair growth on the face or body and hair loss on the scalp
- Lead to severe acne
Insulin Resistance
Another hormone that may be involved in PMOS is insulin. Insulin helps the body’s cells uptake glucose from the blood and use it as energy.
Some people have an increased tolerance to insulin, exacerbated by obesity, so they don’t respond to the hormone as well as they should. This condition is called insulin resistance. About 50 to 90 percent of people with PMOS 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 PMOS.
Inflammation
Some evidence suggests that chronic inflammation may play a role in PMOS.
Typically, inflammation happens when your immune system responds 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, contributing to PMOS symptoms.
Excess body fat acts like an active hormone factory, pumping out signals that increase inflammation, while cutting back on helpful, insulin-boosting hormones (like adiponectin). This blocks cells from effectively absorbing sugar and forces the body to produce even more insulin.
Inflammation can also affect how well the ovaries function, stopping the follicles from evolving normally and leading to PMOS.
Obesity
Obesity is common among people with PMOS, affecting 38 to 88 percent of those with the disorder.
The link between obesity and PMOS is complex. While it isn’t entirely clear which one causes the other, the two are very closely linked: Obesity seems to increase PMOS risk, and vice versa.
Insulin resistance also plays a role. It’s more difficult to lose weight or maintain a healthy weight with insulin resistance. 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 PMOS. It may be the case that people with a genetic predisposition toward obesity are also more prone to developing PMOS.
Either way, reducing obesity and overweight may go a long way in preventing and managing PMOS, 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 PMOS by raising levels of cortisol, the body’s stress hormone. People with PMOS tend to have higher stress levels, research suggests.
High cortisol levels from heightened stress may make it harder for your body to use insulin. This may worsen PMOS.
To help manage PMOS after receiving a diagnosis, try to prioritize rest, relaxation, and other strategies for stress relief.
Resources We Trust
- Cleveland Clinic: Polyendocrine Metabolic Ovarian Syndrome (PMOS)
- Eunice Kennedy Shriver National Institute of Child Health and Human Development: PCOS Resources
- John Hopkins Medicine: PMOS Diet
- Office on Women’s Health: Stress and Your Health
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
- Polycystic Ovary Syndrome. World Health Organization. January 22, 206.
- Polyendocrine Metabolic Ovarian Syndrome (PMOS). Mayo Clinic. May 21, 2026.
- Is Polyendocrine Metabolic Ovarian Syndrome Genetic? Cleveland Clinic. February 7, 2024.
- What Causes PCOS? Eunice Kennedy Shriver National Institute of Child Health and Development Office of Communications. August 21, 2024.
- Palumbo M et al. PCOS and the Genome: Is the Genetic Puzzle Still Worth Solving? Biomedicines. August 5, 2025.
- Moore AM. Neuroendocrine Mechanisms Responsible for Elevated Gonadotrophin‐Releasing Hormone and Luteinising Hormone Pulses in Polycystic Ovary Syndrome. Journal of Neuroendocrinology. April 18, 2025.
- Insulin. Cleveland Clinic. January 17, 2024.
- Insulin Resistance. Cleveland Clinic. November 21, 2024.
- Barber TM et al. Obesity and Polycystic Ovary Syndrome: Implications for Pathogenesis and Novel Management Strategies. Therapeutic Advances in Reproductive Health. September 9, 2019.
- Zhu J-L et al. Sex Hormone-Binding Globulin and Polycystic Ovary Syndrome. Clinica Chimica Acta. September 13, 2019.
- Polyendocrine Metabolic Ovarian Syndrome (PMOS). Cleveland Clinic. February 15, 2023.
- Inflammation. Cleveland Clinic. March 22, 2024.
- Aboeldalyl S et al. The Role of Chronic Inflammation in Polycystic Ovarian Syndrome—A Systematic Review and Meta-Analysis. International Journal of Molecular Sciences. March 8, 2021.
- Orisaka M et al. Chronic Low-Grade Inflammation and Ovarian Dysfunction in Women With Polycystic Ovarian Syndrome, Endometriosis, and Aging. Frontiers in Endocrinology. December 13, 2023.
- Barber TM. Why Are Some Women With Polycystic Ovary Syndrome Obese? British Medical Bulletin. March 12, 2022.
- Altaf K et al. Role of Stress in Onset of Polycystic Ovarian Syndrome (PCOS). Journal of Health and Rehabilitation Research. December 31, 2023.
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Anna L. Goldman, MD
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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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