What is polyendocrine metabolic ovarian syndrome (PMOS)?
Polyendocrine metabolic ovarian syndrome (PMOS) is a complex hormonal condition affecting how a woman’s ovaries function due to an imbalance of reproductive hormones. Until recently, it was known as PCOS (Polycystic ovary syndrome).
PMOS causes the ovaries to produce abnormal androgens (male sex hormones). Hormones regulate the ovaries, which release eggs to be fertilised. These eggs develop in follicles (sacs). If the hormones which trigger the eggs' release from the follicles aren't present in the right amount, they will remain in the follicle. This has the appearance of cysts on ultrasound. Women with ovaries that don't have a cyst-like appearance can also be diagnosed with PMOS.
Why has PCOS been renamed PMOS?
An expert team, made up of some of the world's leading endocrinologists, say the term 'polycystic' in PCOS has led to confusion: "...the term PCOS is inaccurate, implying pathological ovarian cysts, obscuring diverse endocrine and metabolic features, and contributing to delayed diagnosis, fragmented care, and stigma, while curtailing research and policy framing."
International societies and patient groups around the world have campaigned over 14 years. The name change was announced in world-leading medical journal The Lancet, and at the European Congress of Endocrinology in May 2026.
A report in The Guardian highlights that when the condition was named PCOS in the 1930s, doctors initially thought the condition was a disease of the ovaries. Research since then has found PMOS is caused by hormone imbalance and affects multiple systems in the body, but the name PCOS has contributed to misperceptions that it's solely a gynaecological condition.
Who is at risk of developing PMOS?
PMOS can affect women of all races and ethnicities, who are of a childbearing age.
If a patient has a mother or sister with the condition or other hormonal disorders, they are at significantly higher risk of developing PMOS.
Symptoms can appear when a woman starts menstruating during puberty, or start to present following substantial weight gain.
How common is PMOS?
It's very common. According to Verity - The UK PCOS charity, it affects over 4 million women and girls in the UK. Many, up to 70 per cent of those with PMOS, are unaware of their condition.
What causes PMOS?
The exact cause of this condition is unknown. It is suspected that several factors play a role, including:
- genetics
- lifestyle factors
- insulin resistance
- chronic inflammation
- high androgen levels
What are the symptoms of PMOS?
Symptoms of PMOS may include:
- periods that are irregular, very light, or non-existent
- excess body hair/growth (hirsutism)
- metabolic changes including unexplained weight gain, extreme difficulty losing weight, fatigue and insulin resistance which can cause dark skin patches in skin creases
- acne and/or oily skin
- male pattern baldness or thinning hair
- anxiety, depression, mood swings, sleep disturbances such as sleep apnoea, and distress over body image.
Can PMOS affect fertility?
PMOS, which disrupts ovulation and menstrual cycles due to hormone imbalance, is one of the leading causes of female infertility. However it is treatable. People often don’t realise they have PMOS until they experience difficulties conceiving.
Approximately 70-80 per cent of people with PMOS will struggle to get pregnant because the eggs that haven't been released interfere with ovulation, preventing fertilisation.
Can PMOS affect pregnancy?
Having PMOS does not always cause infertility. You can still conceive, but it may be more challenging.
There is an increased risk of pregnancy complications for someone with PMOS, such as miscarriage, giving birth prematurely, getting gestational diabetes, or experiencing high blood pressure brought on by pregnancy.
Women with PMOS are more likely to need a C-section when delivering their baby.
What other complications can PMOS lead to?
People with PMOS can develop serious health problems, such as:
- type 2 diabetes
- high blood pressure
- cardiovascular issues
- high cholesterol
- endometrial cancer
- sleep apnoea
- mood disorders
- anxiety or depression
- steatohepatitis (severe liver inflammation)
When should you seek medical advice on PMOS?
If you are experiencing any of the aforementioned symptoms (inconsistent periods, excessive hair, acne or weight gain) and they are affecting your quality of life, you should seek medical advice.
Additionally, if you are struggling to conceive after 12 months of trying, you should visit your doctor.
How is PMOS diagnosed?
Although there is no singular test that can diagnose PMOS, an early diagnosis can reduce the risks of long-term complications.
A doctor will take a detailed medical history and focus on symptoms. A range of physical exams will be done, such as a pelvic exam, to check for abnormal growths on the ovaries or uterus. Blood tests, to determine hormone, cholesterol and insulin levels, may also be performed. An ultrasound might also be used to look for cyst-like appearance on the ovaries.
If you have at least two of the three main features - irregular periods, excess androgen and/or ovaries that appear polycystic - you may be diagnosed with PMOS. You may be referred to an endocrinologist for specialist treatment.
How is PMOS treated medically?
Treating PMOS depends on varies factors such as your age, severity of symptoms, general wellbeing and whether you’re trying to get pregnant or not.
PMOS has mostly treated with lifestyle changes, such as nutrition, sleep, exercise, mental health assistance.
The following medication can also help:
- ovulation medication, if trying to get pregnant
- birth control
- diabetes medication
- medication to treat symptoms like acne or hair growth
Can PMOS be treated with surgery?
If medication and lifestyle changes do not help, surgery may be considered. Laparoscopic ovarian drilling (LOD) is a procedure that uses heat or laser to eradicate the ovarian tissue responsible for producing the androgens.
Can PMOS be cured?
There is no cure for PMOS, but symptoms can be managed and risks can be reduced with treatment.
PMOS can go away in some women when they go through menopause, but in some cases, hormonal imbalance continues as women age.
How is PMOS managed?
Regular doctor visits are recommended to test for potential conditions that can develop from PMOS.
Leading a healthy lifestyle can reduce the symptoms of PMOS. A healthy diet and doing physical activity for 30 minutes three times a week can improve symptoms.
Additionally, if someone is suffering from poor self-image, perhaps because of weight gain, excess body hair, or acne, cosmetic treatments like laser hair removal are available.
