New NHS guidance recommends that up to 4 million women with irregular periods should be investigated for polyendocrine metabolic ovarian syndrome (PMOS), a condition that experts say has long been underdiagnosed and managed inconsistently across the country.
New guidance targets earlier diagnosis
The National Institute for Health and Care Excellence (Nice) has published draft guidelines calling for GPs to suspect PMOS in any person aged 10 or over whose menstrual cycles fall outside the normal range. Under the proposals, patients should be offered blood tests to measure hormone levels, and in some cases ultrasounds to examine the ovaries. The guidance explicitly states that PMOS should not be discounted in women who have been through the menopause, nor in those with eating disorders — a group disproportionately affected by the condition.
The draft, which is open for public consultation until 11 August 2026 and due to be finalised in December 2026, covers girls aged over 10, adult women, trans men and non-binary people who are not receiving gender reassignment therapy or surgery. It is based on the international evidence-based guideline produced by Monash University, which is already used by more than 100 countries.
Condition and its risks
PMOS — previously known as polycystic ovarian syndrome, or PCOS — is believed to affect up to 13% of women of reproductive age globally, according to the World Health Organization. In the UK, that translates to roughly 3 to 4 million individuals, or about one in eight women. Despite its prevalence, Nice estimates that around 50% of women with PMOS may not have a recorded diagnosis, with some reports suggesting more than a third wait longer than four years for a diagnosis.
The condition was officially renamed from PCOS to PMOS in May 2026 following an international expert consensus published in The Lancet. The new name is intended to reflect its multisystemic nature — extending beyond the ovaries to metabolic and endocrine dysfunction — and to correct the misleading emphasis on ovarian cysts, which are not always present and are not the defining feature.
Symptoms include irregular, very short, long or absent periods; excess levels of testosterone (hyperandrogenism); and ovaries with multiple small follicles visible on ultrasound. Other common symptoms are acne, excess hair growth, hair thinning on the scalp, and weight gain.
PMOS is associated with significantly increased risks of serious long-term health problems. Women with the condition are approximately four times more likely to develop type 2 diabetes, and over half develop it by age 40. They also face greater risks of cardiovascular disease, sleep apnoea, fatty liver disease, mental health issues and complications in pregnancy. Studies suggest people with PMOS are four to seven times more likely to suffer from depression and anxiety, and 8.47 times more likely to attempt suicide. The condition is also one of the most common causes of infertility in women.
Ethnicity plays a significant role in both prevalence and symptom severity. PMOS can be more prevalent among Black, Asian and mixed-ethnicity women, and Nice says healthcare professionals should consider this when assessing symptoms. Women from Black and Asian backgrounds are up to 2.5 times more likely to be diagnosed with the condition, and those from ethnic minority backgrounds are more likely to present with severe symptoms such as insulin resistance. The manifestations differ: South Asian women have a higher prevalence of metabolic syndrome, while women of African descent are prone to hypertension and cardiovascular disease.
Diagnosis and management
The new guidance aims to address what Nice describes as “frequently underdiagnosed and inconsistently managed” care. Under the draft, GPs should suspect PMOS in individuals aged 10 or over whose menstrual cycles are shorter than 21 days or longer than 45 days, or cycles exceeding 90 days at least a year after their first period. For those more than three years after their first period and not in perimenopause, suspicion should be raised for cycles shorter than 21 days or longer than 35 days, or fewer than eight cycles per year. Suspected PMOS is also indicated if a period has not occurred by age 15, or three years after breast development, or in individuals with signs of hyperandrogenism even if they have regular cycles.
Once diagnosed, people with PMOS should be offered an annual review to monitor symptoms such as menstrual irregularities and excess hair growth. The review must also address cardiovascular health, diabetes risk, obesity, mental health care and other associated risks. The guidance recommends that IVF should be offered to women with PMOS who meet the standard Nice criteria for IVF. However, laser hair removal or light therapies for excess hair growth should not be offered, because Nice’s analysis concluded they are not cost-effective — a decision that could save the NHS up to £100 million a year in England.
Expert reaction
Marieanne Ledingham, consultant clinical advisor for women’s and reproductive health at Nice, said: “PMOS is a common but often overlooked condition that can have a major impact on health and wellbeing. Recommending a simple annual review is an important step towards ensuring people get the ongoing care and monitoring they need. This new guideline will help improve consistency of care, increase awareness of the condition, and support earlier diagnosis and management.”
Dr Rachel Reid-McCann, a researcher at Oxford University and author of an earlier study of period pain in The Lancet, said: “Not only can irregular periods be burdensome in the short term, but they have also been associated with longer-term chronic health and reproductive outcomes, making prompt investigation important. A PMOS diagnosis in those with irregular periods can open up access to treatment, support and advice that can help improve symptoms and may also reduce longer-term health risks. The key challenge will be ensuring NHS services have the resources needed to implement these recommendations and doing so consistently across the UK.”
Janet Lindsay, chief executive of the women’s health charity Wellbeing of Women, said: “For too long, women with [PMOS] have faced delays in diagnosis and inconsistent care. Too often, symptoms such as irregular periods, fertility difficulties or concerns about weight have been dismissed as something they must simply live with. Wellbeing of Women welcomes these draft Nice guidelines, recognising [PMOS] as a complex, lifelong condition that can affect reproductive health, mental wellbeing and long-term health outcomes. The recommendation for regular review is an important step towards ensuring women receive the ongoing support, monitoring and information they need throughout their lives. It is particularly encouraging to see the guideline acknowledge the inequalities that persist in diagnosis and care. Women from black, Asian and other minoritised communities can face additional barriers to investigation and diagnosis, and tackling these disparities is essential if everyone is to receive timely, evidence-based care.”