PCOS involves an imbalance of hormones, but the exact cause is unknown. While researchers have established that both hereditary and environmental factors influence a woman’s risk for developing PCOS, no one has identified why some women get PCOS and some women don’t. Most scientists believe PCOS is most likely caused by a combination of inherited and environmental factors.

Risk Factors for PCOS

It is important to note that while science is good at finding correlations, or apparent relationships, between various factors and elevated risk for PCOS, correlation does not prove that the factor causes the condition. Many risk factors for PCOS have been identified and are being studied, but none have been pinpointed as the cause of PCOS.

Overall risk of developing PCOS for any woman in the general population is between 6 and 12 percent.

Hereditary Factors

PCOS does not appear to be directly inherited from parents in a clear genetic pattern. However, women with a mother or sister who has PCOS have up to a 50 percent chance of developing the syndrome themselves. Therefore, it is most likely caused, at least in part, by a mutation in one or more genes. Research to better understand the role of hereditary predisposition in PCOS is ongoing.

Ethnic background seems to play a role in the prevalence of PCOS. Women of Chinese descent have the lowest rate of PCOS. Those with European and Middle Eastern background are affected at higher rates. Women of African and Hispanic descent have the highest risk for PCOS.

Environmental Factors

Weight plays a key role in PCOS. Being overweight exacerbates insulin resistance, menstrual cycle irregularity, and many other symptoms of PCOS. Research shows that PCOS symptoms lessen or disappear in many women when they are at a healthy weight, but symptoms return with weight gain. Eating well and getting exercise can help reduce PCOS symptoms.

Women who have type 1 diabetes or gestational diabetes are also at greater risk for developing PCOS.

Recent research using animals has led to the theory that PCOS may be caused by chemical or genetic changes in the womb.

Condition Guide

• PCOS – An Overview
• PCOS - The Path to Diagnosis
• Symptoms of PCOS
• Treatments for PCOS
• Types of PCOS

Resources

External resources

• What causes PCOS? - Eunice Kennedy Shriver National Institute of Child Health and Human Development
• Polycystic Ovary Syndrome (PCOS) - American College of Obstetricians and Gynecologists
• Polycystic Ovary Syndrome - Office on Women’s Health
• The prevalence of polycystic ovary syndrome in reproductive-aged women of different ethnicity: a systematic review and meta-analysis - Oncotarget
• Racial and ethnic differences in the polycystic ovary syndrome metabolic phenotype - American Journal of Obstetrics and Gynecology
• Racial and ethnic differences in the prevalence of metabolic syndrome and its components of metabolic syndrome in women with polycystic ovary syndrome: a regional cross-sectional study - American Journal of Obstetrics and Gynecology
• What is polycystic ovarian syndrome? - PCOS Awareness Association
• PCOS: Symptoms and Causes - Jean Hailes for Women’s Health

FAQ

Can PCOS be prevented?
PCOS cannot be prevented, although staying in a healthy weight range can help manage PCOS symptoms. While it can be difficult, losing even 10 or 15 pounds can help regulate the menstrual cycle. Other benefits of weight loss for women with PCOS are better cholesterol and insulin levels and a reduction of acne and facial or body hair growth.