PMOS (PCOS)

What it is

PMOS, short for , is a long-term hormone condition. Until May 2026 it was called polycystic ovary syndrome, or PCOS. It affects about 1 in 8 women, more than 170 million worldwide.¹ Up to 70% of people with it have never been diagnosed.²

Myth: PCOS means you have cysts on your ovaries.

The old name made this an easy thing to believe, and doctors used it for decades. Researchers now know there is no increase in abnormal cysts on the ovaries.¹ The name was changed in 2026, after 14 years of work by 56 patient and professional groups, because it pointed people at the ovaries instead of the hormones and metabolism, and that led to missed diagnoses.¹ Cysts are not needed for a diagnosis.²

The signs

affects hormones, metabolism, skin, weight, mental health and fertility.¹ Common signs include:²

periods that are irregular, unpredictable or missing
extra hair on the face or body (hirsutism)
acne or oily skin
thinning hair on the scalp
trouble getting pregnant

These come from the ovaries making more androgens, hormones like testosterone, than usual. PMOS is the cause in about 80 to 90% of women with high .³

Not everyone has every sign. Someone can have PMOS without extra hair, and without anything showing on an ultrasound.^2,4

One story: She was told she couldn't have it because she didn't have extra body hair, and later because an ultrasound showed no cysts. Neither is required for a diagnosis.

One story: Her cycles ran 30 to 40 days, and she assumed that was normal as long as a period came each month. She had no idea some people can predict the day their period will start.

How it's diagnosed

Doctors first rule out other causes of the same signs. Then, under the 2023 international guideline:^2,4

Adults need two of these three: irregular or missing periods, signs of high (on the skin or in a blood test), and ovaries that look polycystic on ultrasound or a high AMH blood test.
Teens need both irregular cycles and signs of high androgens. Ultrasound and aren't used to diagnose it in teens.⁴

Why diagnosis matters

isn't only about periods. People with it have a higher risk of type 2 diabetes, high blood pressure and cholesterol, heart disease, and a thickened or cancerous uterine lining. Anxiety, depression, eating disorders and a negative body image are more common too.² Knowing about it means these can be checked for and treated early.

Its cause is unknown, but it runs in families, and having a relative with type 2 diabetes also raises the risk.² There is no cure, and treatment is built around each person's symptoms. See the WHO fact sheet for an overview.

What to track and ask

Track for a few months: the dates of each period, acne and hair growth, weight changes, and mood.

Questions to ask:

Could this be ? What else should we rule out?
Should my blood sugar, blood pressure and cholesterol be checked?
What are my options for my main symptom?

When to see a doctor

See a doctor if you've missed three periods in a row, your periods have become irregular, or you've missed a period and also notice weight gain or loss, facial hair growth, or oily skin.⁵

AMH (anti-Müllerian hormone)	A hormone made by growing follicles, measured with a blood test.
androgens	Hormones such as testosterone. Everyone makes them; people with PMOS often make more.
hirsutism	Coarse, dark hair growing on the face, chest, belly or back in a male-like pattern.
PMOS (polyendocrine metabolic ovarian syndrome)	A common long-term hormone condition, formerly called polycystic ovary syndrome (PCOS).