What causes PCOS?
What is the main cause of PCOS?
Although the exact cause of PCOS still mystifies the scientific community, the condition likely results from a combination of genetic and lifestyle factors, including family history, insulin resistance, hormone imbalances, and weight. There’s increasing evidence that stress may contribute, too.
Experts can’t say for sure what causes PCOS. But the following factors are believed to play an important role.
PCOS and genetics
There’s some evidence to suggest PCOS runs in families (1). If your mother, sister, or aunt has PCOS, there’s an increased risk of developing it. And this may be higher in some ethnic groups. However, no single gene has been linked to the condition (2).
It’s also worth mentioning that despite this genetic component, it doesn’t always mean you’ll have it. Individuals with a genetic predisposition are more vulnerable to PCOS, but the necessary environmental conditions must be present (3). Think of your genes as lights in your house: environmental factors can switch them on and off.
PCOS and insulin resistance
Insulin resistance is thought to be another potential cause of PCOS. Around 70 per cent of women with PCOS experience insulin resistance, which means their cells can’t use insulin correctly (4).
A hormone produced by the pancreas, insulin balances the amount of sugar in the blood. It helps move glucose from the blood into cells, where it’s broken down to generate energy.
But if the cells can’t use insulin efficiently, the body’s demand for insulin increases. The pancreas then produces more insulin to compensate. And this causes insulin resistance.
Excess insulin stimulates the ovaries to produce more androgens, ‘male’ hormones, like testosterone, which can lead to many hallmark PCOS symptoms, including menstrual irregularities, acne, and hirsutism (excess hair growth).
There’s some debate over whether elevated androgens cause insulin resistance or insulin resistance causes elevated androgen levels. It most likely depends. Some women experience insulin resistance first; others have high androgens first.
Insulin resistance can also cause weight gain, which often exacerbates PCOS symptoms, as it makes the body produce even more insulin.
Insulin resistance is associated with an increased risk for type-2 diabetes, too. You also learn more about the connection between PCOS and diabetes here.
PCOS and hormone imbalances
For many women, hormone imbalances may be behind their PCOS. Although more research is needed, it may result from insulin resistance.
Some of the hormone imbalances include (5):
Increased testosterone levels – often regarded as a ‘male’ hormone
Increased levels of luteinising hormone (LH) – this hormone triggers ovulation but may have an unusual effect on the ovaries if too high
Lower levels of sex hormone-binding globulin (SHBG) – a protein in the blood that binds to testosterone and reduces its impact
H3: PCOS and weight
PCOS can affect women of all sizes. However, carrying more weight may increase the hormonal changes responsible for PCOS symptoms.
Even losing 5-10 per cent of body weight can help balance hormone production and improve many PCOS symptoms (6). You can find out more about losing weight with PCOS safely and effectively here.
Is PCOS caused by stress?
While there’s a genetic component of PCOS, stress is increasingly thought to play a role in its development.
From poor sleep and working demanding hours to caring for ageing parents and body image concerns, stress is an unavoidable part of modern life. Elevated stress may cause ‘adrenal-dominant PCOS’ where elevated androgens trigger symptoms similar to ovarian-dominant PCOS (7).
Acute stress vs. chronic stress
It’s important to recognise the difference between acute stress and chronic stress to understand the relationship between stress and PCOS.
Acute stress is a short-term experience. It happens in response to a perceived threat, such as having a near miss on the road.
Acute stress activates the body’s evolutionary stress response, otherwise known as ‘fight, flight or freeze’. This releases the hormone, cortisol, to prepare itself to react in the face of danger.
Physiologically speaking, this response increases heart rate, ramps up breathing, and decreases digestive activity. But once the threat is no longer present, the stress subsides, and the body recovers.
Chronic stress, on the other hand, leaves the body in a state of constant emergency. It happens when the body remains stuck in the ‘fight, flight, or freeze’ response. Daily elevated cortisol levels can affect every system in the body.
How can chronic stress lead to PCOS?
PCOS is characterised by elevated androgens, ‘male’ hormones that lead to many challenging symptoms. Most of the literature focuses on the ovarian production of androgens, which is often triggered by high insulin.
But the adrenal glands – which mainly make the hormones involved in the stress response, like cortisol, adrenaline, and noradrenaline – also produce androgens. Chronic stress can send the adrenal glands into overdrive, leading to the excessive production of androgen hormones.
As a result, a woman could have normally functioning ovaries and no insulin resistance, but still experience adrenal-dominant PCOS.
Chronic stress is often overlooked for its role in PCOS. But it can be a main driver of the condition.
You can read more about supporting your mental health with PCOS here.
Find out more
PCOS is a complex hormonal condition. Although experts are still unsure what causes PCOS, it most likely results from genetic and lifestyle factors. Fortunately, you can manage many of them.
If you found this look into PCOS causes useful, you can find similar guidance on our dedicated PCOS health hub. Alternatively, please get in touch with our team of expert Nutrition Advisors, who are on hand to provide free, confidential advice.
Ajmal N, Khan SZ, Shaikh R., Polycystic ovary syndrome (PCOS) and genetic predisposition: A review article. European Journal of Obstetrics & Gynecology and Reproductive Biology: X. 3, p. 100060. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6571926/
Khan MJ, Ullah A, Basit S., Genetic Basis of Polycystic Ovary Syndrome (PCOS): Current Perspectives. Applied Clinical Genetics. 12, p. 249-260. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6826506/
Ilie. I.R, Georgescu. C.E. (2016). Polycystic Ovary Syndrome-Epigenetic Mechanisms and Aberrant MicroRNA. Adv Clin Chem. 71:25-45.
Marshall JC, Dunaif A., Should all women with PCOS be treated for insulin resistance? Fertility and Sterility. 97(1), p. 18-22.
NHS choices. (2022) Available online: https://www.nhs.uk/conditions/polycystic-ovary-syndrome-pcos/causes/
Moran LJ, Brinkworth GD, Norman RJ., Dietary therapy in polycystic ovary syndrome. Seminars in Reproductive Medicine. 26(1), p. 85-92.
Yildiz BO, Woods KS, Stanczyk F, Bartolucci A, Azziz R., Stability of adrenocortical steroidogenesis over time in healthy women and women with polycystic ovary syndrome. The Journal of Clinical Endocrinology & Metabolism. 89(11), p. 5558-62.
Disclaimer: The information presented by Nature's Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.
Olivia Salter has always been an avid health nut. After graduating from the University of Bristol, she began working for a nutritional consultancy where she discovered her passion for all things wellness-related. There, she executed much of the company’s content marketing strategy and found her niche in health writing, publishing articles in Women’s Health, Mind Body Green, Thrive and Psychologies.