PMOS phenotypes: the 4 Rotterdam types (A, B, C, D)
PMOS (formerly PCOS) is not one single condition — it has four recognised phenotypes. Knowing which one fits your picture helps explain why two people with the same diagnosis can have very different symptoms, metabolic risk and treatment priorities. This page explains the four Rotterdam phenotypes in plain language.
Where the phenotypes come from
The four phenotypes are built from the three Rotterdam criteria (2003), confirmed by the 2023 international evidence-based guideline:
- 1. Hyperandrogenism — clinical (acne, excess hair growth, hair loss) or biochemical (raised androgens on a blood test).
- 2. Ovulatory dysfunction — irregular, infrequent or absent periods.
- 3. Polycystic ovarian morphology — many small follicles or increased ovarian volume on ultrasound, or a high AMH used as an alternative marker.
A diagnosis requires at least two of the three criteria, after excluding other conditions (see our blood tests for PMOS guide). The specific combination of criteria you meet defines your phenotype.
The 4 phenotypes at a glance
| Phenotype | Hyperandrogenism | Ovulatory dysfunction | Polycystic morphology | Typical metabolic risk |
|---|---|---|---|---|
| A — full / classic | Yes | Yes | Yes | Highest |
| B | Yes | Yes | No | High |
| C — ovulatory | Yes | No (broadly regular) | Yes | Intermediate |
| D — non-hyperandrogenic | No | Yes | Yes | Lowest (still monitored) |
Metabolic risk is a general tendency reported across studies, not an individual prediction. Your own risk depends on weight, family history, age and lifestyle.
The 4 phenotypes in detail
Phenotype A — full (classic)
All three criteria are present. This is generally the most metabolically demanding phenotype, with the highest reported rates of insulin resistance, and a greater long-term tendency toward type 2 diabetes and metabolic syndrome. Close cardiometabolic monitoring (HbA1c, lipids, blood pressure) is usually a priority.
Phenotype B — hyperandrogenic, no polycystic morphology
Hyperandrogenism plus ovulatory dysfunction, but without polycystic morphology on ultrasound. The cardiometabolic profile is generally close to phenotype A, so similar metabolic monitoring usually applies.
Phenotype C — ovulatory
Hyperandrogenism plus polycystic morphology, with broadly regular cycles. Spontaneous fertility may be preserved. Skin-related symptoms (acne, excess hair growth, hair loss) often dominate the picture, so dermatological management tends to take priority.
Phenotype D — non-hyperandrogenic
Ovulatory dysfunction plus polycystic morphology, without hyperandrogenism. This is usually the least metabolically severe phenotype, but it still requires follow-up because cycle and metabolic patterns can change over time.
Why phenotype changes your care
Phenotype is one of the clearest illustrations of why the condition was renamed from PCOS to PMOS in 2026: it is not purely an ovarian problem. The phenotypes that carry the metabolic features (A and B in particular) sit at the heart of the “M” — metabolic — in PMOS. Phenotype helps your clinician decide where to focus: tight cardiometabolic monitoring for the more severe phenotypes, and more dermatological or fertility-focused care for others. For the broader background, see the 2026 renaming.
Frequently asked questions
What are the 4 PMOS phenotypes?
The Rotterdam framework defines four PMOS / PCOS phenotypes from three criteria (hyperandrogenism, ovulatory dysfunction, polycystic ovarian morphology). Phenotype A has all three; Phenotype B has hyperandrogenism + ovulatory dysfunction (no polycystic morphology); Phenotype C (ovulatory) has hyperandrogenism + polycystic morphology with broadly regular cycles; Phenotype D (non-hyperandrogenic) has ovulatory dysfunction + polycystic morphology without hyperandrogenism.
Which PMOS phenotype is the most severe?
Phenotype A (the "full" or "classic" phenotype, with all three criteria) is generally the most metabolically severe, with the highest rates of insulin resistance and cardiometabolic risk. Phenotype B is close behind. Phenotype D is usually the least metabolically severe, but it still warrants monitoring.
Can my PMOS phenotype change over time?
Yes. Phenotype is a snapshot based on current symptoms, cycles and imaging. It can shift with age, weight changes, treatment, or as ovarian morphology evolves — for example, androgen symptoms may ease after menopause. This is why diagnosis is reviewed in clinical context rather than fixed for life.
How do I find out which PMOS phenotype I have?
Only a doctor can confirm your phenotype, using your symptoms, blood tests (androgens, and tests to exclude other conditions) and, where relevant, a pelvic ultrasound or AMH. Our phenotype quiz can give you an orientation to discuss at your appointment, but it is not a diagnosis.
Main sources
- International Evidence-based Guideline 2023 (Monash) — diagnostic criteria and phenotypes
- NIH / NICHD — PCOS information
- ACOG — Polycystic Ovary Syndrome (PCOS) FAQ
Page written from official public sources. It does not constitute a diagnosis or personalised medical advice. Only your doctor can confirm your phenotype.