Polyendocrine Metabolic Ovarian Syndrome (PMOS)

Formerly known as Polycystic Ovary Syndrome (PCOS)

Polyendocrine Metabolic Ovarian Syndrome (PMOS) is one of the most common hormonal conditions affecting women and girls of reproductive age. It is a complex condition that can affect menstruation, fertility, hormones, metabolism, skin health and emotional wellbeing.

In 2026, an international consensus recommended changing the name from Polycystic Ovary Syndrome (PCOS) to Polyendocrine Metabolic Ovarian Syndrome (PMOS). The new name better reflects the condition, as it involves multiple hormone systems and metabolic health—not just the ovaries. During the transition period, both names may still be used by healthcare professionals and in health information resources.

Although PMOS is a lifelong condition, it can be effectively managed. Early diagnosis and treatment can improve symptoms, protect long-term health and help individuals achieve their personal health and fertility goals.

What is PMOS?

PMOS is a hormonal condition that affects how the ovaries function. Many people with PMOS do not release an egg regularly (ovulate), resulting in irregular menstrual cycles and difficulty becoming pregnant.

The condition is also associated with higher-than-normal levels of androgens, hormones that are present in everyone but are normally found in lower amounts in women. Increased androgen levels may lead to symptoms such as acne, excessive facial or body hair, and thinning hair on the scalp.

Many people with PMOS also have insulin resistance, where the body’s cells do not respond effectively to insulin. Over time, this can increase the risk of developing type 2 diabetes and other metabolic conditions.

Despite its previous name, most people with PMOS do not have ovarian cysts. Instead, the ovaries may contain many small immature follicles that have not developed enough to release an egg.

How Common is PMOS?

PMOS affects an estimated 8–13% of women of reproductive age worldwide, making it one of the most common hormonal disorders.

Many people remain undiagnosed because symptoms develop gradually, vary from person to person or are mistaken for other conditions.

What Causes PMOS?

The exact cause of PMOS is unknown. It is thought to develop through a combination of genetic and environmental factors.

Several factors contribute to the condition.

• Hormonal Imbalances

Hormonal changes interfere with normal ovulation and affect menstrual cycles.

• Insulin Resistance

Many people with PMOS have insulin resistance. When the body becomes less responsive to insulin, it produces more insulin to compensate. High insulin levels can stimulate the ovaries to produce more androgens, worsening symptoms.

• Genetics

PMOS often runs in families. Having a mother or sister with the condition increases the likelihood of developing it.

Researchers continue to study why some people develop PMOS while others do not.

Signs and Symptoms

Symptoms vary considerably. Some people have only one or two symptoms, while others experience several.

Common symptoms include:

•	irregular, infrequent or absent periods;
•	heavy menstrual bleeding after long gaps between periods;
•	difficulty becoming pregnant due to irregular ovulation;
•	persistent acne;
•	excessive hair growth on the face, chest, abdomen or back (hirsutism);
•	thinning hair or hair loss from the scalp;
•	weight gain or difficulty losing weight;
•	darkened patches of skin, particularly around the neck, underarms or groin (acanthosis nigricans); and
•	small skin tags, especially around the neck or under the arms.

Not everyone with PMOS experiences all of these symptoms.

How Does PMOS Affect the Menstrual Cycle?

Ovulation may occur infrequently or not at all. Without regular ovulation, menstrual periods become irregular.

Some people experience:

•	fewer than eight periods a year;
•	months without a period;
•	unpredictable menstrual cycles; or
•	heavy bleeding after a prolonged absence of menstruation.

Irregular periods should always be discussed with a healthcare professional, particularly if they continue over several months.

Can PMOS Affect Fertility?

Yes. Because ovulation may not occur regularly, becoming pregnant can be more difficult.

However, PMOS does not mean someone cannot have children.

Many people with PMOS conceive naturally. Others become pregnant with lifestyle changes, medication or fertility treatment.

How is PMOS Diagnosed?

There is no single test that can diagnose PMOS.

A healthcare professional will consider:

•	menstrual history;
•	symptoms;
•	medical and family history;
•	physical examination;
•	blood tests to measure hormone levels and rule out other conditions; and
•	a pelvic ultrasound where appropriate.

Many healthcare professionals use internationally recognised diagnostic criteria, which require at least two of the following:

•	irregular or absent ovulation;
•	signs or blood test evidence of elevated androgen levels; or
•	ovaries with multiple immature follicles seen on ultrasound.

Other medical conditions that cause similar symptoms must first be excluded.

Possible Health Complications

Without appropriate management, PMOS may increase the risk of:

•	infertility;
•	type 2 diabetes;
•	high blood pressure;
•	high cholesterol;
•	heart disease;
•	obstructive sleep apnoea;
•	anxiety and depression;
•	endometrial hyperplasia (thickening of the lining of the uterus); and
•	endometrial cancer due to prolonged absence of ovulation.

Regular medical care helps reduce these risks.

Treatment

There is currently no cure for PMOS, but treatment can effectively manage symptoms and reduce the risk of complications.

Treatment depends on an individual’s symptoms, health goals and whether pregnancy is desired.

Healthy Lifestyle

Regular physical activity, a balanced diet and maintaining a healthy weight can improve hormone balance, insulin sensitivity and menstrual regularity for many people.

Medicines

Healthcare professionals may prescribe medicines to:

•	regulate menstrual cycles;
•	improve insulin sensitivity;
•	reduce androgen levels;
•	treat acne or excessive hair growth; or
•	stimulate ovulation for people wishing to become pregnant.

Treatment should always be individualised.

Living with PMOS

PMOS is a lifelong condition, but many people live healthy, fulfilling lives with appropriate care.

Helpful strategies include:

•	attending regular medical check-ups;
•	monitoring menstrual cycles;
•	maintaining a balanced diet;
•	engaging in regular physical activity;
•	taking prescribed medicines as directed; and
•	seeking support for emotional wellbeing when needed.

When Should You See a Healthcare Professional?

Seek medical advice if you:

•	have irregular or absent periods;
•	experience very heavy periods after long gaps;
•	have persistent acne that does not respond to treatment;
•	develop excessive facial or body hair;
•	notice thinning hair on your scalp;
•	have difficulty becoming pregnant after trying to conceive;
•	gain weight unexpectedly together with menstrual changes; or
•	notice dark patches of skin around the neck, armpits or groin.

Early diagnosis can improve symptom control and reduce the risk of long-term complications.

Myths and Facts

Myth: PMOS only affects people who are overweight.
Fact: PMOS can affect people of any body size.

Myth: Everyone with PMOS has ovarian cysts.
Fact: Most people with PMOS do not have ovarian cysts. The ovaries may contain multiple immature follicles rather than true cysts.

Myth: PMOS means you will never have children.
Fact: Many people with PMOS become pregnant naturally or with appropriate medical support.

Myth: Missing periods is harmless.
Fact: Long gaps between periods should always be assessed because they can increase the risk of changes to the lining of the uterus over time.

Frequently Asked Questions

• Can teenagers develop PMOS?

Yes. Symptoms often begin during adolescence. However, diagnosing PMOS in teenagers can be challenging because irregular periods are common during the first few years after menstruation begins.

• Is PMOS curable?

No. There is currently no cure, but symptoms can usually be managed successfully with treatment and healthy lifestyle changes.

• Does everyone with PMOS gain weight?

No. PMOS affects people of all body sizes.

• Can lifestyle changes improve symptoms?

Yes. For many people, regular physical activity, healthy eating and maintaining a healthy weight improve menstrual regularity, insulin sensitivity and overall health.

• Why was the name changed from PCOS to PMOS?

The previous name focused on ovarian cysts, even though most people with the condition do not have cysts. The new name better reflects the hormonal, metabolic and reproductive nature of the condition.

Key Messages

•	Polyendocrine Metabolic Ovarian Syndrome (PMOS), formerly known as Polycystic Ovary Syndrome (PCOS), is one of the most common hormonal conditions affecting women and girls of reproductive age.
•	PMOS affects hormones, metabolism, menstrual cycles and fertility.
•	Not everyone with PMOS has ovarian cysts or is overweight.
•	Irregular periods, acne, excessive hair growth and difficulty becoming pregnant are common symptoms.
•	Early diagnosis and treatment can improve symptoms and reduce the risk of long-term health complications.
•	Many people with PMOS go on to have healthy pregnancies and lead healthy lives with appropriate medical care.

Knowledge Hub Series: Period Talk Uganda – Evidence-Based Menstrual Health Resources