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Your guide to polycystic ovary syndrome (PCOS)
Affecting up to one in eight women, polyendocrine metabolic ovarian syndrome (PMOS), formerly known as polycystic ovary syndrome (PCOS), is the most common cause of fertility problems caused by irregular or absent ovulation. Recognising the symptoms early is important, as it allows timely management of symptoms, reduces long-term metabolic health risks, and helps optimise your chances of conceiving.
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In this guide:
PMOS is a major factor that can impact your metabolic and reproductive health. Whether you've been aware of your PMOS for a while or have recently received a diagnosis, we are here to support you on your fertility journey.
In this guide, we cover:
- What PMOS is and its causes
- Why was the name changed from PCOS to PMOS
- Common signs and symptoms to look out for
- How the condition affects your fertility
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What is PCOS?
Polyendocrine metabolic ovarian syndrome (PMOS), formerly known as polycystic ovary syndrome (PCOS), is a hormonal and metabolic condition that affects how the ovaries function. Women can develop PMOS at any age after puberty, but it is most commonly diagnosed in their twenties or thirties.
PMOS may lead to irregular menstrual periods, cause increased levels of androgens (male hormones), which can lead to excessive facial and body hair. Some people with PMOS may also have enlarged ovaries containing multiple small follicles, which are immature fluid-filled sacs that surround the eggs. The exact cause of PMOS is unclear and not everyone with the condition will experience symptoms.
What does the PMOS rename mean?
The term PCOS (polycystic ovary syndrome) has been deemed misleading, as it suggests that the condition specifically leads to cysts on the ovaries, which is not always true. It is believed that the term "polycystic" has contributed to delays in diagnosis and inadequate medical care for those affected.
The name PMOS (polycystic metabolic ovarian syndrome) is proposed to better reflect the complexity of the condition, which affects not only the reproductive system but also metabolism and is associated with an increased risk of type 2 diabetes and cardiovascular risk factors.
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What causes PMOS?
While the exact cause of PMOS remains unclear, it is recognised as a complex condition influenced by a combination of genetic, hormonal, and environmental factors. If a biological family member has PMOS, your risk of developing it may be higher.
For many individuals with PMOS, insulin resistance plays an important role. The body's cells do not respond properly to the hormone insulin, so the pancreas produces extra insulin to compensate. This excess insulin can stimulate the ovaries to produce too much testosterone, an androgen hormone. High levels of testosterone can disrupt normal follicle development and prevent regular ovulation, contributing to many of the features of PMOS.
Furthermore, PMOS is often associated with hormonal imbalances, including elevated levels of androgens like testosterone, as well as high levels of luteinising hormone (LH), which promotes ovulation. However, if LH levels are excessively high, it can interfere with ovulation.
What are the symptoms of PMOS?
Symptoms of PCOS or PMOS often begin after puberty, although many people are diagnosed in their twenties or thirties. Not everyone will exhibit signs of the condition, and symptoms can vary in intensity. It's essential to be aware of the symptoms and contact your doctor if you have any concerns.
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Common signs of PCOS
Most women who experience this condition may display various symptoms, including irregular or absent menstrual periods, difficulty conceiving, weight gain, oily skin, acne, thinning hair or hair loss from the head (androgenetic alopecia), and excessive hair growth (hirsutism) on the face, chest, back or buttocks.
Less common signs of PCOS
In many cases, individuals with PMOS may experience an increased risk of high blood pressure, high cholesterol, type 2 diabetes, anxiety and depression and sleep apnoea. While the absolute risk remains very low, a history of irregular periods is associated with an increased risk of endometrial cancer, which can be reduced with appropriate cycle management and medical care.
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When to see a doctor
PMOS can impact individuals in different ways, especially for those who are trying to start a family.
If you're concerned about any symptoms you are experiencing, contact your doctor for advice and guidance.
How does PCOS affect fertility?
PCOS, now referred to as PMOS, impacts fertility in several ways. It disrupts ovarian function, which can hinder ovulation and the release of eggs. This is mainly due to hormonal imbalances, particularly elevated levels of androgens, often referred to as male hormones. The main effect is reduced or irregular ovulation, which can make it more difficult to conceive.
It's important to acknowledge that other factors, such as age, lifestyle, and underlying medical conditions, can also influence fertility.
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The difference between PCOS and polycystic ovaries
Polycystic ovaries (PCO) and PMOS (formerly known as PCOS) are related, but they are not the same. PCO refers to the presence of multiple small follicles in the ovaries and is considered a physical characteristic that can be seen on an ultrasound. In contrast, PMOS is a complex hormonal and metabolic disorder that affects women of reproductive age, leading to imbalances in hormone levels.
It is important to understand that not everyone with polycystic ovaries necessarily has PMOS, and having PCO alone isn't sufficient for a diagnosis. If you have any concerns, it's essential to consult your doctor.
Fertility treatment options
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Fertility drugs
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In vitro fertilisation (IVF)
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Intrauterine insemination (IUI)
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Intracytoplasmic sperm injection (ICSI)
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Egg freezing
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Donation
PCOS and PMOS FAQs
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Dr Kausar Jabeen
Verified clinicianFertility Consultant , TFP Thames Valley Fertility · Reviewed 2 August 2026
Demonstrated Experience
- ·Over 20 years of experience in obstetrics and gynaecology.
- ·Manages complex fertility cases and early pregnancy complications.
- ·Has authored several book chapters and published numerous articles in peer-reviewed journals, regularly presenting her research at national and international conferences.
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