In May 2026, one of the most significant changes in women’s hormonal health in decades was announced by The Lancet. PCOS (Polycystic Ovary Syndrome) has been renamed PMOS (Polyendocrine Metabolic Ovarian Syndrome), or PMOS. Why is changing the name of the condition so important? Will the change really affect women living with it?
Here’s what the change actually means, and why it matters.
What is PMOS, and why did the name change?
PMOS (Polyendocrine Metabolic Ovarian Syndrome) – previously known as PCOS is a condition that affects the function of a woman’s ovaries. As defined by the NHS, three symptoms are attributed to PCOS (now PMOS):
- Irregular periods
- Excess androgen (high levels of “male” hormones)
- Polycystic ovaries
The symptoms- and the confusion surrounding them- are why the name of the condition has been changed from PCOS to PMOS.
Understanding how PMOS is diagnosed
The term “polycystic” has long been one of the most confusing parts of this diagnosis. It implies that ovarian cysts are a defining feature of the condition. They’re not and they never were! What an ultrasound actually identifies are small, arrested follicles (the fluid-filled sacs that eggs develop inside), not cysts. Many people with the condition show no particular ovarian changes on ultrasound at all, while others have the classic appearance on a scan but no symptoms whatsoever.
PCOS vs PMOS: Why is the change important?
Confusion of the diagnosis criteria has led to real consequences for women living with PCOS. The NHS is clear that only two of three diagnostic criteria need to be met for a diagnosis, and a scan isn’t always required. Yet the name “PCOS” implied otherwise, creating the impression that ovaries, and specifically cysts, were the defining part of the diagnosis story.
According to The Lancet, up to 70% of those with PMOS remain undiagnosed, with the inaccurate name cited as a direct contributor to knowledge gaps, delayed diagnosis, and widespread patient dissatisfaction with care.
What does PMOS stand for?
Polyendocrine
PMOS isn’t driven by one rogue hormone: it involves a complex interaction between testosterone, insulin, oestrogen, progesterone, LH, and FSH, all of which can play a role. “Poly” meaning many, “endocrine” refers instead to the hormonal system. Together, these words finally communicate what research has shown for years: this is a whole-body hormonal condition, not simply an ovarian one.
Metabolic
Despite insulin resistance being present in around 80% of people with PMOS, it has never been part of the diagnostic criteria. When insulin isn’t working effectively, the body produces more of it in compensation. Excess insulin stimulates the ovaries to produce more androgens, which drives metabolic dysfunction, raising the long-term risk of Type 2 and gestational diabetes, high cholesterol, non-alcoholic fatty liver disease, and cardiovascular disease.
Ovarian
Irregular ovulation, unpredictable periods, disordered follicular development, and elevated anti-Müllerian hormone (AMH) remain central features of PMOS. Ovarian disturbances can affect conception, contribute to infertility, and (in the context of irregular or absent menstrual bleeding) may also increase the risk of endometrial cancer over time.
Syndrome
Carried over from the original name, “syndrome” reflects that PMOS is a cluster of symptoms and signs rather than a single diagnostic marker. Whilst a diagnosis of PMOS requires at least two of three recognised criteria, the condition presents differently from one person to the next. Redefined, PMOS honours that complexity by keeping the door open for a personalised approach to care.
What does this mean for PMOS diagnosis?
The diagnostic criteria themselves are not changing immediately. The 2023 International Evidence-Based PCOS Guideline remains the current standard, with integration into the new PMOS framework planned for the 2028 update.
Diagnostic criteria for PCOS/PMOS
A diagnosis of PMOS in adults requires two of the following three:
- Irregular or infrequent periods indicate the ovaries are not regularly releasing eggs
- Clinical or biochemical hyperandrogenism, elevated testosterone, or signs such as excess hair growth or acne
- Polycystic ovarian morphology onultrasoundor, since 2023, an elevated AMH level as an alternative
If two criteria are present, a diagnosis can be made without a scan, without waiting, and without cysts.
How will PCOS/PMOS treatment change?
The name change places insulin resistance firmly at the centre of how PMOS is understood and treated. That matters enormously for how it should be managed.
By recognising hyperinsulinaemia as a key driver of androgen excess, irregular cycles, acne, and metabolic risk, treatment plans will more effectively target the underlying mechanism, rather than managing individual symptoms.
The role of myo-inositol in PMOS treatment
Myo-inositol is an important part of PMOS treatment. In PMOS, an imbalance between myo-inositol and D-chiro-inositol can cause impaired insulin sensitivity and disrupted egg development. A 2024 systematic review conducted to inform the International Guideline update found that myo-inositol showed benefits for certain metabolic outcomes and potential improvements in ovulation, with a favourable safety and tolerability profile.
Inositol treatment now sits alongside other evidence-informed nutritional approaches, which include omega-3 fatty acids and vitamin D, as part of the metabolic features now reflected in the PMOS name.
PMOS: Breaking the stigma
Beyond the clinical detail, this name change carries a wider significance. PMOS is not solely a fertility condition: i. It is not something that only affects people who are overweight. And it is not something that becomes irrelevant once reproductive considerations are off the table. It is a complex, lifelong, multisystem condition that affects metabolic health, cardiovascular health, psychological wellbeing, and quality of life, and it deserves to be treated as such.
The global consensus process revealed that stigma avoidance was the single most important priority for patients. The old name, with its misleading language around cysts and its narrow focus on reproductive organs, contributed to confusion and a long-standing sense that women with PCOS/PMOS were not being fully understood.
Changing the name from PCOS to PMOS will not solve everything. But it is a meaningful step towards better diagnosis, better care, and a clearer conversation between patients and the clinicians supporting them.
References
Endocrine Society (2026) Polyendocrine metabolic ovarian syndrome: new name to improve diagnosis and care of condition affecting 170 million women worldwide. Available at: https://www.endocrine.org/news-and-advocacy/news-room/2026/pcos-name-change (Accessed: 22 May 2026).
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Tay, C.T., Mousa, A., Vyas, A., Pattuwage, L., Tehrani, F.R. and Teede, H. (2024) ‘2023 international evidence-based polycystic ovary syndrome guideline update: insights from a systematic review and meta-analysis on elevated clinical cardiovascular disease in polycystic ovary syndrome’, Journal of the American Heart Association, 13, e033572. doi: 10.1161/JAHA.123.033572.
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Teede, H.J., Tay, C.T., Laven, J.J.E., Dokras, A., Moran, L.J., Piltonen, T.T., Costello, M.F., Boivin, J., Redman, L.M., Boyle, J.A., Norman, R.J., Mousa, A. and Joham, A.E. (2023) ‘Recommendations from the 2023 international evidence-based guideline for the assessment and management of polycystic ovary syndrome’, Journal of Clinical Endocrinology & Metabolism, 108(10), pp. 2447–2469. doi: 10.1210/clinem/dgad463.
Tewari, S., Khalua, R.K. and Parida, S. (2026) ‘Redefining polycystic ovary syndrome (PCOS) as polyendocrine metabolic ovarian syndrome (PMOS): implications for diagnosis, pathophysiology and clinical management’, International Journal of Gynaecology Sciences, 8(1a), pp. 17–25. doi: 10.33545/26648393.2026.v8.i1a.55.
The ObG Project (2026) Polyendocrine metabolic ovarian syndrome (formerly PCOS): making the diagnosis. Available at: https://www.obgproject.com/2016/12/09/polycystic-ovary-syndrome-making-diagnosis/ (Accessed: 22 May 2026).
