PMOS Explained: Why PCOS Got a New Name — and Why It Was Never About Cysts

Hands cupping a halved pomegranate on cream linen — the seeds echo the stalled follicles seen in PMOS, the new name for PCOS

If you were told you have polycystic ovary syndrome, you were probably also handed a mental picture: ovaries studded with cysts, like bubble wrap. It’s a vivid image. It’s also wrong. PMOS — polyendocrine metabolic ovarian syndrome — is the new name for PCOS, adopted by a global consensus published in The Lancet in May 2026. The condition hasn’t changed. What’s changed is that the name finally describes it: a lifelong, whole-body hormonal and metabolic condition that happens to become visible at the ovaries.

There are no cysts. There never were. And once you let go of that word, a lot of things — why it affects slim women, why “just lose weight” so often fails, why your bloods matter more than your scan — start to make sense.

Quick take · screenshot this

PMOS in 60 seconds

  • PMOS = PCOS. Same condition, corrected name; both will appear on paperwork until 2028.
  • The “cysts” on a scan are normal follicles that stalled — not cysts.
  • It’s a whole-body endocrine & metabolic condition, not an ovary problem with side effects.
  • Insulin resistance drives most cases — including in slim women.
  • Diagnosis = 2 of 3: irregular ovulation, androgen excess, follicle-rich ovaries (AMH can now stand in for the scan).
  • Your type matters more than your label.

Everything below is simply this, slowed down and explained.

What is PMOS? Why PCOS got a new name

A woman in a black top reading a letter in warm light with a calm, thoughtful expression — making sense of a PMOS diagnosis

In May 2026, after a fourteen-year process, polycystic ovary syndrome was formally renamed polyendocrine metabolic ovarian syndrome (PMOS). The consensus was published in The Lancet, led by Professor Helena Teede at Monash University with the Androgen Excess & PCOS Society and the UK patient charity Verity, and endorsed by 56 organisations including the American Society for Reproductive Medicine and the Endocrine Society (Teede et al., 2026). More than 14,000 patients and health professionals across every world region had their say — and it was the women living with the condition who pushed hardest for change.

This isn’t a rebrand. It’s a correction — and the new name puts the emphasis where it belongs:

  • Poly-endocrine — several hormone systems are involved: insulin, androgens, and the brain’s pulse-generator for the ovaries.
  • Metabolic — how your body handles insulin, glucose and energy is central, not incidental.
  • Ovarian — the ovaries are where the condition becomes visible and where it affects ovulation and fertility.

A three-year transition is under way, with full adoption in the 2028 guideline update. Until then you’ll see both names, often written PCOS/PMOS. Same condition, same criteria, same treatments — a more honest label.

So what were those “cysts”?

Follicles. Perfectly normal ones, each containing an egg.

What an ultrasound actually shows in PMOS is an excess of small, immature follicles that started developing, stalled partway, and accumulated around the edge of the ovary. Every one of them is a normal structure. They simply never got the hormonal permission to finish the job. The consensus authors are blunt about it: the word “polycystic” implied pathological ovarian cysts that aren’t there, and a substantial proportion of women diagnosed with the condition have nothing of the kind (Teede et al., 2026).

Cysts versus follicles: what a PMOS scan actually shows Two ovary diagrams side by side. Left, the myth: large fluid-filled cysts, crossed out. Right, the reality: a ring of twenty or more small follicles, each containing an egg, that have stalled before ovulation. Footer: no cysts, no surgery needed, a hormonal traffic jam driven by insulin and androgens. There are no cysts in PMOS The “polycystic” ovary, as imagined — and as it really is THE MYTH What people picture Large, fluid-filled “cysts” that need draining or removing. THE REALITY What the scan actually shows 20+ small follicles (2–9 mm), each holding an egg — stalled, not diseased. No cysts. No surgery needed. A hormonal traffic jam — follicles start, stall and accumulate. Driven by insulin and androgens, which is why the condition was renamed polyendocrine metabolic ovarian syndrome. Evidence-based · Dr Helena Cepparo myfertilitypod.com
Cysts versus follicles: what a PMOS scan actually shows Two ovary diagrams stacked. Top, the myth: large fluid-filled cysts, crossed out. Bottom, the reality: a ring of twenty or more small follicles, each containing an egg, that have stalled before ovulation. There are no cysts in PMOS As imagined — and as it really is THE MYTH What people picture Large, fluid-filled “cysts” that need draining or removing. THE REALITY What the scan actually shows 20+ small follicles (2–9 mm), each holding an egg — stalled, not diseased. No cysts. No surgery needed. A hormonal traffic jam driven by insulin and androgens. Evidence-based · Dr Helena Cepparo myfertilitypod.com
The “polycystic” ovary as people picture it (left) versus what a scan actually shows (right): a ring of small, stalled follicles — no cysts.

That one misleading word did real damage. It framed a whole-body endocrine and metabolic condition as a gynaecological one, sent women to the wrong clinics, and delayed diagnosis by years.

How is PMOS diagnosed?

Diagnosis still uses the Rotterdam criteria: two out of three features in adults, once thyroid disease, raised prolactin and congenital adrenal hyperplasia have been excluded (Teede et al., 2023):

  1. Ovulatory dysfunction — cycles shorter than 21 days or longer than 35 days, from three years after your first period until perimenopause.
  2. Hyperandrogenism — clinical (hirsutism, jawline acne, scalp hair thinning) or biochemical (raised free testosterone or free androgen index).
  3. Polycystic ovarian morphology — 20 or more follicles measuring 2–9 mm in at least one ovary, or an ovarian volume of 10 ml or more.

The genuinely useful update: since 2023, AMH can replace ultrasound for that third criterion in adults. Because anti-Müllerian hormone is made by exactly those small stalled follicles, blood levels track follicle count closely — and unlike a scan, AMH doesn’t depend on the machine, the sonographer, or the day of your cycle (Piltonen et al., 2024). One caveat: thresholds still vary by age, BMI and laboratory, so there’s no universal cut-off yet.

In adolescents, neither is used. Multifollicular ovaries and irregular cycles are simply too normal in puberty to mean anything. (For which tests belong in a first work-up, see when to start fertility testing.)

The engine room: insulin and androgens

Insulin is usually the villain of the piece — and not in the way most people assume.

Insulin resistance affects roughly 70% of women with PMOS who carry excess weight and, crucially, 30–50% of those who are slim. This is not a body-size problem. A 2026 analysis found that HOMA-IR — a simple index of insulin resistance from a fasting blood test — predicted the hyperandrogenic phenotype independently, even after adjusting for BMI, while BMI itself lost statistical significance altogether (Frontiers in Endocrinology, 2026).

The insulin–androgen loop in PMOS A four-step cycle. One: insulin rises because cells resist it and the pancreas makes more. Two: the ovary makes more testosterone because its androgen signalling still works, and the liver makes less SHBG. Three: more free androgen, causing acne, hair changes and stalled follicles. Four: androgens worsen insulin resistance, and the loop repeats. In the centre: follicles stall, AMH rises, no dominant follicle, no ovulation, no progesterone. Footer: break the loop at step one with food pattern, movement and sleep, then metformin or inositol if needed. The insulin–androgen loop Why PMOS is a metabolic condition that shows up at the ovary Insulin rises1Cells resist insulin, so the pancreas makes moreOvary makesmore testosterone2Its androgen signallingstill works — and the livermakes less SHBGMorefree androgen3Acne, hair changes — and follicles stallInsulinresistance worsens4Androgens blunt insulinfurther — and roundit goes THE RESULT Follicles stall AMH rises · no dominant follicle no ovulation · no progesterone Break the loop at step 1: food pattern, movement, sleep — then metformin or inositol if needed. Evidence-based · Dr Helena Cepparo myfertilitypod.com
The insulin–androgen loop in PMOS A four-step cycle shown as a vertical list: insulin rises; the ovary makes more testosterone; more free androgen; insulin resistance worsens, and the loop repeats. Result: follicles stall, AMH rises, no ovulation, no progesterone. Break the loop at step one. The insulin–androgen loop Why PMOS shows up at the ovary 1Insulin risesCells resist insulin, so thepancreas makes more of it2Ovary makes more testosteroneIts androgen signalling still works;the liver also makes less SHBG3More free androgenAcne, hair changes —and follicles stall4Insulin resistance worsensAndrogens blunt insulin further— and round it goesROUND IT GOES THE RESULT Follicles stall AMH rises · no ovulation · no progesterone Break the loop at step 1 Food pattern, movement, sleep — then metformin or inositol. Evidence-based · Dr Helena Cepparo myfertilitypod.com
The insulin–androgen loop: why PMOS is a metabolic condition that shows up at the ovary — and where to break the cycle.

The mechanism is almost darkly elegant. Ovarian tissue becomes resistant to insulin’s metabolic signalling while its androgen-making signalling stays perfectly intact. So as your body compensates by producing more insulin, the ovary doesn’t hear “take in more glucose.” It hears “make more testosterone.” Insulin also suppresses the liver’s output of sex hormone binding globulin (SHBG), so more of that testosterone circulates freely — and the androgens then worsen the insulin resistance. Round it goes.

The result is follicular arrest. Follicles start, stall, and keep pumping out AMH, which blunts the ovary’s sensitivity to FSH and stops any one follicle becoming dominant. No ovulation, no progesterone, no period. It’s also why the metabolic basics do so much heavy lifting in PMOS — they act on the engine, not the paintwork (our 90-day preparation plan covers those levers).

Not one condition: phenotypes and the four functional types

Formally, PMOS is sorted into Rotterdam phenotypes A to D. Phenotype A (all three features) carries the heaviest metabolic load; phenotype D, without hyperandrogenism, is usually mildest.

In functional and integrative practice — the lens I work through alongside conventional fertility medicine — you’ll more often meet a four-type framework, popularised by Lara Briden, the naturopathic doctor and author of Period Repair Manual, Hormone Repair Manual and Metabolism Repair for Women. Briden has spent nearly thirty years in women’s health and is a peer-reviewed author, co-writing with endocrinology professor Jerilynn Prior on the neuroendocrine origins of androgenic PMOS (Briden, Shirin & Prior, 2020). Her four types are listed in order of priority — the part most people miss:

Four women of different ages walking together at a sunny market carrying bags — PMOS presents differently in every woman
  • Insulin-resistant — by far the most common. If insulin resistance is present, that’s your type, even if you also have inflammation or came off the pill last year. Treat the insulin first.
  • Post-pill — a temporary androgen rebound after stopping hormonal contraception, typically settling within one to two years. Briden’s point here is important: this often isn’t PMOS at all, and treating it as a lifelong diagnosis does real harm.
  • Inflammatory — driven by chronic immune activation rather than blood sugar, and flagged by markers like CRP.
  • Adrenal — raised DHEA-S with otherwise normal ovarian androgens, roughly 20–30% of cases. Told to “just cut carbs and take metformin,” these women get nowhere, because their androgens aren’t coming from the ovary.

Clinical note: no androgen excess, no PMOS.

Briden is refreshingly strict about diagnosis, and this is where functional medicine earns its keep. If you don’t have raised androgens, clinically or biochemically, the diagnosis needs revisiting: hypothalamic amenorrhoea from under-eating produces multifollicular ovaries too, and congenital adrenal hyperplasia accounts for up to 9% of androgen excess and is routinely mislabelled. Same scan, opposite treatment.

Her other contribution is cyclic progesterone therapy. The reasoning: in PMOS, GnRH pulses too fast, driving chronic LH stimulation of the ovarian theca cells and pushing out androgens. Progesterone normally slows those pulses — but you only make progesterone by ovulating, which is precisely what isn’t happening. The combined pill delivers a predictable bleed and lower androgens, but doesn’t touch the underlying neuroendocrine problem. Body-identical progesterone, given cyclically, might. The honest caveat: the mechanistic case is strong, the short-term data are encouraging, and we still lack the long-duration randomised trials to call it proven.

Where the functional lens helps — and where it overreaches

Let’s be clear-eyed. The four types are a clinical heuristic, not a validated classification. They don’t appear in the international guideline or in any endocrinology textbook. What they are is a practical map of real physiological differences that helps direct treatment — which matters when the same four-letter diagnosis can mean four different things.

Two areas where the functional approach is genuinely ahead of the curve:

Inflammation. Raised IL-6, TNF-α and CRP have been documented in ovarian tissue, follicular fluid, fat tissue and the endometrium in PMOS. This is increasingly understood as intrinsic to the condition, not incidental (Zhang et al., 2024).

The gut. Studies consistently show reduced microbial diversity, depletion of beneficial short-chain-fatty-acid producers, and raised markers of barrier disruption such as zonulin (Lindheim et al., 2017). The proposed chain — dysbiosis → increased permeability → endotoxin translocation → inflammation → worse insulin resistance → more androgen — is mechanistically coherent. It is also, for now, largely associative. Support the gut sensibly (see the gut–hormone connection); don’t let anyone sell you a protocol as though it were settled.

Encouragingly, the two worlds are converging. The inositol review that informed the 2023 guideline was led by integrative medicine researchers at Western Sydney University’s NICM Health Research Institute (Fitz et al., 2024). Around 70% of women with PMOS use complementary medicine — and, tellingly, a similar proportion name the thin evidence base as its main drawback (Arentz et al., 2014). They’re right to.

💬 Been told to “lose some weight and come back in a year”?

That’s a label, not a plan. If you’d like someone to look at your bloods, cycle history and symptoms together — and tell you honestly which type of PMOS you’re dealing with and what to do about it — I offer one-to-one video consultations from wherever you are. No packages, no protocols for sale.

Book a Video Consultation

What actually works for PMOS

Hands placing fresh salad leaves onto a plate in a bright cream kitchen — lifestyle is first-line treatment for PMOS

Lifestyle comes first, and the evidence is refreshingly undogmatic — no single diet or exercise regimen beats any other (Cowan et al., 2023). The guideline explicitly asks clinicians to minimise weight stigma and to ask permission before weighing you. And sleep is a metabolic lever in its own right.

For fertility: letrozole is now first-line for ovulation induction, outperforming clomiphene on live births — 27.5% versus 19.1% in the landmark trial — with fewer twins (Legro et al., 2014). Gonadotrophins or ovarian drilling follow; IVF is third-line.

For cycles and androgen symptoms when you’re not trying to conceive: combined oral contraceptives remain first-line, with cyclic body-identical progesterone a reasoned alternative if you can’t tolerate them.

On supplements, honesty beats enthusiasm. The guideline concluded that metformin outperforms inositol, and that specific inositol doses and combinations can’t yet be recommended (Teede et al., 2023; Fitz et al., 2024). That said, myo-inositol with D-chiro-inositol at 40:1 has decent data for insulin sensitivity and ovulation, an excellent safety profile, and is a defensible adjunct (Nordio et al., 2019). Vitamin D repletion, omega-3s, zinc and NAC all have supportive short-term data. Scaffolding, not substitutes.

Treatment · in order of evidence

The PMOS toolkit, ranked honestly

  • Lifestyle — food pattern, movement, sleep: first-line for everyone, any body size
  • Letrozole — first-line to ovulate if you’re trying to conceive
  • Metformin — for insulin resistance and metabolic risk
  • Combined pill or cyclic progesterone — for cycles, androgens and lining protection
  • Inositol 40:1, vitamin D, omega-3 — reasonable adjuncts, not cures

Anyone promising to “reverse” PMOS with a single supplement is selling something.

The bottom line

  • PMOS is the new name for PCOS. There are no cysts — just stalled follicles.
  • It’s a whole-body endocrine and metabolic condition that shows up at the ovaries, not an ovarian condition with side effects.
  • Insulin resistance drives most cases, including in slim women.
  • Your type matters more than your label. Insulin-resistant, adrenal, inflammatory and post-pill presentations need genuinely different plans.
  • No androgen excess? The diagnosis deserves a second look.
  • It’s lifelong, so cardiovascular and metabolic risk should be assessed regardless of your BMI (Henney et al., 2025) — and the endometrium needs protecting when cycles are absent.

When personalised guidance makes the difference

If your periods have always been unpredictable, if you’ve been handed a PMOS diagnosis with a prescription and very little explanation, or if you’ve been told to “lose some weight and come back in a year” — you deserve better than that.

The most useful next step is finding out what’s actually driving your picture. These numbers, not the label, should shape what happens next:

Ask for these · the PMOS work-up

The blood tests that reveal your type

  • Fasting insulin & glucose (HOMA-IR), HbA1c — is insulin resistance the driver?
  • Total testosterone, SHBG → free androgen index — is there androgen excess at all?
  • DHEA-S — are the androgens adrenal rather than ovarian?
  • AMH — the follicle count, from a blood test
  • TSH, prolactin, 17-hydroxyprogesterone — the look-alikes that must be excluded
  • hs-CRP — an inflammatory signal worth knowing

Ideally fasting, early in a cycle, and off hormonal contraception for three months.

🩺 Unsure whether it’s PMOS — or what to do now that it is?

Whether you’re questioning a diagnosis, trying to conceive with PMOS, or simply want a plan built around your bloods rather than your BMI, you’re very welcome to talk it through with me. One-to-one video consultations worldwide, in English or Italian — conventional fertility medicine with a root-cause, functional-medicine lens.

Book a Video Consultation

Questions patients ask me every week

The real questions from clinic — answered directly, without the vagueness.

Is PMOS the same as PCOS?

Yes. Polyendocrine metabolic ovarian syndrome (PMOS) is the new name for polycystic ovary syndrome (PCOS), adopted by a global consensus published in The Lancet in May 2026 and endorsed by 56 organisations. The condition, the diagnostic criteria and the treatments are unchanged; only the name has been corrected. Both names will be used during a transition period running to 2028.

Why was PCOS renamed PMOS?

Because the old name was inaccurate and harmful. “Polycystic” implied pathological cysts that don’t exist — the structures seen on a scan are normal follicles that have stalled — and it framed a whole-body hormonal and metabolic condition as a purely gynaecological one, contributing to delayed diagnosis, fragmented care and stigma. PMOS names the three things that matter: multiple hormone systems, metabolism, and the ovary.

Do I have cysts on my ovaries if I have PMOS?

No. What shows on ultrasound in PMOS is a high number of small, immature follicles (2–9 mm) that began developing and stalled. They are normal structures, each containing an egg, and they do not need removing or draining. True ovarian cysts are a separate finding and are not more common in PMOS.

How is PMOS diagnosed?

In adults, by having two of three Rotterdam features once thyroid disease, raised prolactin and congenital adrenal hyperplasia are excluded: irregular or absent ovulation (cycles under 21 or over 35 days), androgen excess (clinical or on blood tests), and follicle-rich ovaries — 20 or more follicles per ovary or a volume of 10 ml or more on ultrasound, or a raised AMH blood level in place of the scan. In adolescents, only the first two features count.

Can you have PMOS if you’re slim?

Yes. Roughly 30–50% of slim women with PMOS have insulin resistance, and research shows insulin resistance predicts the androgen-excess form of the condition independently of BMI. Body size neither causes nor rules out PMOS, which is why fasting insulin and metabolic testing matter at every weight.

What are the four types of PCOS/PMOS?

In functional medicine, PMOS is often sorted into insulin-resistant, post-pill, inflammatory and adrenal types, in that order of priority. This is a practical clinical heuristic rather than a validated classification; the official system is Rotterdam phenotypes A to D. The functional types are useful because they point to different drivers — insulin, a temporary androgen rebound after contraception, chronic inflammation, or adrenal DHEA-S — which need different treatment.

Can I get pregnant with PMOS?

Very often, yes. PMOS is one of the most treatable causes of infertility because the eggs are there — the problem is ovulation. Lifestyle change restores ovulation in many women; if not, letrozole is first-line for ovulation induction (27.5% live birth versus 19.1% with clomiphene in the landmark trial), followed by gonadotrophins, and IVF as third-line, to which women with PMOS usually respond well.

Does PMOS go away after menopause?

The ovulation problems stop, but PMOS is lifelong. The metabolic features — insulin resistance, and the raised risk of type 2 diabetes, fatty liver disease and cardiovascular disease — persist beyond menopause, so regular metabolic and cardiovascular checks should continue regardless of age or BMI.

Dr Helena Cepparo

Consultant Gynaecologist & Fertility Specialist · AFMCP Functional Medicine

Over 20 years of experience in reproductive medicine and IVF, with international training across Italy, Canada, Japan and the UK. Dr Cepparo takes a root-cause approach to fertility — integrating evidence-based medicine with functional medicine to create personalised plans. She founded MyFertilityPod to make clear, evidence-based fertility information accessible to everyone. She practises at a private fertility clinic in Central London.

References & Scientific Sources

  1. Teede HJ, Khomami MB, Morman R, et al; Global Name Change Consortium. Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: a multistep global consensus process. The Lancet. 2026;407:2329–2339. doi:10.1016/S0140-6736(26)00717-8
  2. Teede HJ, Tay CT, Laven JJE, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Human Reproduction. 2023;38(9):1655–1679. doi:10.1093/humrep/dead156
  3. Monash Centre for Health Research and Implementation. International Evidence-based Guideline for the Assessment and Management of PMOS/PCOS 2023. monash.edu/medicine/mchri/pcos/guideline
  4. Piltonen TT, Viita-aho J, Saarela U, Melin S, Forslund M. Utility of serum anti-Müllerian hormone measurement as part of polycystic ovary syndrome diagnosis. Seminars in Reproductive Medicine. 2024;42(1):49–59. PMC11257749
  5. Divergent pathophysiological drivers of polycystic ovary syndrome: insulin resistance independently fuels the hyperandrogenic phenotype whilst neuroendocrine factors dominate non-hyperandrogenic presentations. Frontiers in Endocrinology. 2026;17:1758861. doi:10.3389/fendo.2026.1758861
  6. Briden L, Shirin S, Prior JC. The central role of ovulatory disturbances in the etiology of androgenic polycystic ovary syndrome (PCOS) — evidence for treatment with cyclic progesterone. Drug Discovery Today: Disease Models. 2020;32(B):71–82. ScienceDirect
  7. Briden L. 4 types of PCOS (a flowchart). larabriden.com
  8. Fitz V, Graca S, Mahalingaiah S, et al. Inositol for polycystic ovary syndrome: a systematic review and meta-analysis to inform the 2023 update of the International Evidence-based PCOS Guidelines. Journal of Clinical Endocrinology & Metabolism. 2024;109(6):1630–1655. doi:10.1210/clinem/dgad762
  9. Legro RS, Brzyski RG, Diamond MP, et al; NICHD Reproductive Medicine Network. Letrozole versus clomiphene for infertility in the polycystic ovary syndrome. New England Journal of Medicine. 2014;371(2):119–129. doi:10.1056/NEJMoa1313517
  10. Cowan S, Lim S, Alycia C, et al. Lifestyle management in polycystic ovary syndrome — beyond diet and physical activity. BMC Endocrine Disorders. 2023;23:14. doi:10.1186/s12902-022-01208-y
  11. Zhang Y, et al. Systematic low-grade chronic inflammation and intrinsic mechanisms in polycystic ovary syndrome. Frontiers in Immunology. 2024;15:1470283. doi:10.3389/fimmu.2024.1470283
  12. Lindheim L, Bashir M, Münzker J, et al. Alterations in gut microbiome composition and barrier function are associated with reproductive and metabolic defects in women with polycystic ovary syndrome (PCOS): a pilot study. PLOS ONE. 2017;12(1):e0168390. doi:10.1371/journal.pone.0168390
  13. Arentz S, Smith CA, Abbott JA, Bensoussan A. A survey of the use of complementary medicine by a self-selected community group of Australian women with polycystic ovary syndrome. BMC Complementary and Alternative Medicine. 2014;14:472. doi:10.1186/1472-6882-14-472
  14. Henney AE, Gillespie CS, Lai JYM, et al. Risk of type 2 diabetes, MASLD and cardiovascular disease in people living with polycystic ovary syndrome. Journal of Clinical Endocrinology & Metabolism. 2025;110(5):1235–1246. doi:10.1210/clinem/dgae481
  15. Nordio M, Basciani S, Camajani E. The 40:1 myo-inositol/D-chiro-inositol plasma ratio is able to restore ovulation in PCOS patients: comparison with other ratios. European Review for Medical and Pharmacological Sciences. 2019;23(12):5512–5521. PubMed 31298405