Up to 4 million women with irregular periods should be investigated for polyendocrine metabolic ovarian syndrome, according to new NHS guidance.

PMOS, previously known as polycystic ovarian syndrome, is believed to affect up to 13% of reproductive age women, the World Health Organization estimates.

Symptoms include irregular, very short, long or absent periods, excess levels of testosterone, and ovaries with multiple small follicles.

The condition is associated with greater risk of developing type 2 diabetes, cardiovascular disease, sleep apnoea, fatty liver disease, mental health issues and complications in pregnancy.

But the National Institute for Health and Care Excellence (Nice) says that, despite affecting 3- to 4-million women in the UK, PMOS is “frequently underdiagnosed and inconsistenly managed”.

Nice’s new draft guidance covers girls aged over 10, as well as adult women, trans men and non-binary people who are not receiving gender reassignment therapy or surgery.

Patients with suspected PMOS should be offered blood tests including male and female hormone levels and in some cases ultrasounds. PMOS should not be discounted in women who have been through the menopause, or those with eating disorders, which disproportionately affect people with PMOS, the guidance states.

PMOS can be more prevalent among black, Asian and mixed ethnicity women, and the guidance also says healthcare professionals should consider this when assessing symptoms.

Once diagnosed, those with PMOS should have an annual review to monitor symptoms such as menstrual irregularities and excess hair growth. The annual review should discuss cardiovascular health, diabetes, obesity, mental health care and other risks associated with PMOS.

The guidance also states that IVF should be offered for women with PMOS who meet the standard Nice criteria for IVF.

But they should not be offered laser hair removal or light therapies for excess hair growth “because analysis suggests these are not cost-effective ways of improving overall health and wellbeing”, Nice said. It would cost the NHS up to £100m a year in England to offer those treatments to PMOS patients, Nice estimates.

The draft guidance is based on the international evidence-based guideline produced by Monash University and used by more than 100 countries.

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.”

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Consultation on the draft guidelines is open until 11 August 2026, with final guidelines due in December 2026.

Responding to the announcement, 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.”

The chief executive of Wellbeing of Women, Janet Lindsay, 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.”