Polycystic ovary syndrome (PCOS) has recently been renamed Polyendocrine Metabolic Ovarian Syndrome (PMOS). The change, proposed by an international consensus in 2026, reflects a better understanding that the condition is not simply an ovarian disorder but can involve reproductive, hormonal and metabolic systems.
1. Why the name change from PCOS to PMOS? (i.e., in favour)
1a. Not all women have appearance of polycystic ovaries. Per se the word polycystic could be misleading as there are not true ovarian cysts but instead antral (immature) follicles
1b. The syndrome is not primarily ovarian and may involve different systems, have different features and lead to different problems and consequences
2. Is PMOS an accurate representation of the Syndrome? (i.e., against)
2a. Perhaps not as it gives lots of emphasis to “Metabolic” and could overshadow reproductive problems and functions, thus misleading the patients whose primary problem could be reproductive and in turn lead to delays in the management of the issues related to reproduction.
2b. If the argument to have polycystic ovaries in PCOS was that not all women have appearance of polycystic ovaries, then in the new name PMOS not all women have Polyendocrine status, and as such it may stigmatise and misdiagnose certain patients.
3. Symptoms
Symptoms of PMOS can vary considerably between individuals and may also change over time. Some women experience significant symptoms, while for others they may be mild or barely noticeable. PMOS may be diagnosed when at least two of the following features are present:
Irregular periods – Periods may be irregular, infrequent, absent, unusually frequent, heavy or prolonged. PMOS can also make it more difficult to become pregnant.
Excessive androgen – Higher androgen levels can cause excess facial or body hair (hirsutism). They may also contribute to severe acne or male-pattern hair loss.
Polycystic ovaries – Your ovaries may be slightly enlarged and contain many small, fluid-filled follicles that hold immature eggs. Because ovulation may not occur regularly, these eggs are not always released.
4. Causes
Although the exact causes of PMOS are not known, potential causes include:
Insulin resistance – In PMOS, the body may not respond effectively to insulin, the hormone that helps cells use sugar for energy. This can raise blood sugar levels, causing the body to produce more insulin to compensate.
Genes – Women with a family history of PMOS may be more likely to have it themselves, since it could be linked to particular genes.
Androgen levels – Women with PMOS may have increased levels or effects of hormones such as testosterone.
5. PMOS and fertility
PMOS can affect fertility mainly by interfering with regular ovulation. However, having PMOS does not mean that a woman cannot become pregnant. Many women conceive naturally, while others may need treatment to induce ovulation or assisted reproductive treatment such as IVF.
The appropriate treatment depends on the individual and should consider age, ovulation, ovarian reserve, duration of infertility, sperm quality, fallopian tube health and metabolic factors.
Women with PMOS may also respond strongly to ovarian stimulation during IVF, making an individualised treatment protocol particularly important.
6. A personalised approach
The change from PCOS to PMOS highlights an important message: this is a complex condition that can affect women in very different ways.
For some, metabolic health may be the main concern. For others, fertility and reproductive health are the priority. The name may have changed, but treatment should always focus on the individual woman rather than the label.
At NOW-fertility, we take a personalised approach to women with PMOS, considering both their reproductive and overall health when planning fertility treatment.
