What Causes Polycystic Ovary Syndrome in Females

The exact cause of PCOS is unknown to doctors. Research indicates a combination of insulin resistance, hormone imbalance, and family history. Polycystic ovary syndrome is one of the most common hormonal conditions for females, with the Endocrine Society estimating it affects around 1 in 8 women globally – more than 170 million people.

One update first. In May 2026, the condition was renamed polyendocrine metabolic ovarian syndrome, or PMOS, by an international group. It mentions that it used to be called PCOS, but the NHS now uses the new name. This guide uses PCOS because most people still search for it, and everything here applies to both names. Let’s break it down.

Quick answer

• No causative agent has been identified.

• Insulin resistance is the root cause of many cases.

• Insulin and testosterone are examples of hormones that don’t work right.

• Your chances increase if you have a close relative with PCOS.

• Gaining weight alone does not cause PCOS, but it can make the symptoms worse.

Know More : PCOS or PCOD

PCOS Is Now Called PMOS: What the New Name Means

The new name is the result of a global process involving more than 50 patient and professional organisations, the Endocrine Society said. It is supported by the American Society for Reproductive Medicine (ASRM), and the PMOS title is now included on the NHS condition page.

The switch had solved a long-standing problem. The old name implied ovaries filled with cysts. Reports on the renaming say the condition does not involve increased pathological ovarian cysts, and the new name instead shows its hormonal and metabolic side. According to the AAFP blog, the international clinical guideline is expected to adopt the new name in its 2028 update, and the transition is expected to take about three years.

In your appointments, you might hear both names for a while.

What Causes Polycystic Ovary Syndrome?

The NHS says the cause of PCOS is not known, but it could be linked to hormones such as insulin and testosterone not working properly. These are the main things pointed out by researchers and doctors.

Insulin resistance

Insulin is a hormone produced by the pancreas that regulates blood sugar. Insulin resistance means that the body’s tissues do not respond well to insulin, so the body produces more insulin to compensate. Previous NHS guidance on causes said, 'High levels of insulin cause the ovaries to produce too much testosterone. That testosterone boost messes with the follicles, the little sacs where eggs grow, and can prevent normal ovulation.

This condition is often associated with insulin resistance. The AAFP blog says it affects up to 85 per cent of women with PCOS, including about 75 per cent of those with a body mass index of 25 or less. So it can happen in thin women too.

Hormone imbalance

Women with PCOS frequently have hormonal imbalances. According to previous NHS guidance, the problem can start in the ovary itself, in other glands that make these hormones, or in the part of the brain that controls them. Insulin resistance may also cause the changes. Researchers haven’t determined what came first, and the order may be different for different people.

Genetics and family history

PCOS is frequently inherited. If a close family member such as a mother, sister or aunt has it, you could be more likely to get it, the NHS says. Previous NHS guidance adds that no specific genes have been identified. The current NHS page also lists Asian background as a factor that makes you more likely.

Weight and lifestyle

Weight isn’t the answer in every case, but it matters. The NHS guidance says insulin resistance can lead to weight gain, and more body fat then leads to the body producing more insulin. That cycle can make symptoms worse. Habits alone do not cause PCOS, and being slim does not rule it out.

What does not cause PCOS?

Polycystic ovary syndrome is not caused by ovarian cysts. The name was misleading; that’s why experts changed it. The condition is not your fault, and nothing you did or ate caused the condition. So don’t blame yourself.

Risk factors at a glance

• Aunt, sister, or mother with PCOS

• Asian ancestry

• Resistance to insulin

• Weight gain can aggravate symptoms

Symptoms of Polycystic Ovary Syndrome in Females

Symptoms usually start around puberty, often before age 18, and continue until menopause. Some symptoms improve or change after menopause. They may be mild, severe, or absent. The NHS lists these as the main symptoms:

• irregular or long-interval periods

• hair growth, excessive (hirsutism) or hair loss

• difficulty gaining weight or losing weight; difficulty getting pregnant

• anxious and/or depressed

• acne and oily skin

• tired

• thick, dark skin patches on the neck or armpits (acanthosis nigricans)

The NHS says fertility problems often occur because the ovaries do not release an egg every month. Many of these symptoms also have other causes, so if you experience them, it does not mean you have PCOS. A check-up fixes that.

How Doctors Diagnose PCOS

See a GP if you think you might have PCOS or if your symptoms are affecting your daily life, work or relationships. A GP may refer you for tests with a gynaecologist or an endocrinologist, says the NHS. The tests include:

• Blood tests to check hormone levels and insulin resistance.

• An ultrasound scan to examine the ovaries. Only do this if you are 18 or over.

Your doctors will look at your test results and scan together with your symptoms. The diagnosis is not made by one result.

Health Risks Linked to PCOS

Over time, PCOS can increase the chances of some serious conditions. The NHS says:

• diabetes mellitus, type 2

• hypertension

• cardiovascular disease

• fatty liver disease (non-alcoholic)

• cancer of the womb

But you can lower your risk by getting regular check-ups and talking to your doctor if you are worried about any of these risks. Mental health issues as well. Living with PCOS can be difficult physically and emotionally, the NHS says, but talking therapies can help if symptoms trigger depression or anxiety.

Treatment and Lifestyle Changes

There is no cure; treatment relieves symptoms. The NHS says that doctors sometimes use:

• irregular periods – the combined pill, progestogen-only pill or an intrauterine system (IUS)

clomifene for increasing fertility; spironolactone or eflornithine to reduce unwanted hair growth; metformin, a medicine for type 2 diabetes, for tiredness and weight problems; skin creams or tablets for acne; weight loss medicines if you are overweight

If other treatments are unsuccessful, the doctor may suggest laparoscopic ovarian drilling. This process uses heat or a laser to destroy ovarian tissue and may help to release more eggs.

Daily habits help also. Recommended by the NHS:

• Eat a healthy, balanced diet; exercise regularly; if you are overweight, try to lose weight; try talking therapy if symptoms affect your mood

• Removing unwanted hair through shaving, waxing, creams, electrolysis or laser

• The NHS also refers to charities such as Verity for information and peer support.

Testing and Support at a Clinic

Some patients choose a private appointment for quicker access or a longer consultation. PCOS is one of the most common reasons people attend the consultant gynaecologists at myGynae Plus, a West London women’s health clinic, alongside heavy, irregular or painful periods and fertility concerns. Its services page also lists pelvic ultrasound scans and blood tests for hormones like AMH, FSH, LH, oestradiol, thyroid, and prolactin, and accepts self-referrals. Ask the clinic which tests are appropriate for your symptoms. NHS guidance also recommends checking for insulin resistance. Share private results with your GP to ensure your records remain complete.

Next Steps

Book a doctor’s appointment and make a note of your symptoms, your cycle dates and any family history. Request blood tests and scans. If you are over 18 and want extra scans or hormone tests as well as NHS care, a clinic like myGynaePlus does list those services, but your GP is the route for NHS referral. This material is general information and is not a substitute for professional medical advice.

FAQs About Polycystic Ovary Syndrome

What is the main cause of PCOS?

Doctors haven’t found any one cause. The process revolves around insulin resistance and hormone imbalance, especially high testosterone. Family history also increases your risk. Hormones such as insulin and testosterone may not work properly, the NHS says.

Is PCOS genetic?

It often runs in the family. If you have a mother, sister or aunt with PCOS, you are more likely to have it, and the NHS says Asian background is a factor too. No specific genes have yet been identified by researchers.

Can you have PCOS if you are not overweight?

Yes. Weight may exacerbate symptoms, but it is not the cause of the condition by itself. The AAFP blog reports that about 75% of women with a body mass index of 25 or less still have insulin resistance.

Is PCOS the same as PMOS?

Yup. In May 2026, polycystic ovary syndrome was renamed by specialists to polyendocrine metabolic ovarian syndrome. The NHS now uses PMOS, and it’s said to have previously been called PCOS. The condition is still the same.

Can PCOS go away?

There is no cure, but treatment and lifestyle changes ease symptoms. Symptoms often start at puberty and last until menopause. Some symptoms stop or change after menopause, according to the NHS.