Gynaecology
Polyendocrine Metabolic Ovarian Syndrome (PMOS)
Formerly known as Polycystic Ovarian Syndrome (PCOS), this is complex hormonal and metabolic condition that can affect periods, skin, weight, ovulation and overall health.
What is PMOS?
Polyendocrine Metabolic Ovarian Syndrome (PMOS), formerly known as PCOS, is a complex hormonal condition that affects up to 1 in 8 women of childbearing age. It is characterised by an imbalance in endocrine (hormonal) function and metabolism, which can affect ovulation, menstrual cycles and broader aspects of health such as mood, sleep and cardiovascular wellbeing.
What are the causes of PMOS?
The cause of PMOS is unknown but it is thought that several factors could play a role. Genetics in particular are thought to have an influence as women with PMOS are more likely to have a mother or sister with PMOS.
A main underlying problem is a hormonal imbalance:
- Many women with PMOS have too much insulin in their blood because their body does not respond to the normal amount (insulin resistance). The excess insulin has a direct effect on the way the ovary works
- In women with PMOS, the ovaries appear to make more androgens (male hormones) than normal. High levels of these hormones affect the development and release of eggs during ovulation
Why did PCOS change to PMOS?
In May 2026, the name was updated to Polyendocrine Metabolic Ovarian Syndrome (PMOS) to better reflect what the condition involves. While “polycystic ovary syndrome” focuses on the ovaries, it doesn’t fully explain the wider hormonal and metabolic changes that can affect the body.
The term ‘PMOS’ highlights that this condition involves overall hormone balance and metabolic health, not just the appearance of the ovaries.
What are the symptoms of PMOS?
The symptoms of PMOS can vary from woman to woman, but may include:
Infertility
PMOS is often linked to infertility as it impairs the body’s ability to release an egg each month.
Infrequent, absent and/or irregular menstrual periods
If you have very irregular or only sporadic periods, this may be an indication you are not ovulating and you may need medical assistance to have a baby.
Hirsutism (excess body hair)
Increased hair growth on the face, chest, stomach and back can indicate a hormonal imbalance and is often seen in patients with PMOS.
Changes to the ovaries
PMOS is often associated with abnormal follicular development in the ovaries. This can disrupt normal ovulation and may make it more difficult to conceive.
Acne
Because of the hormonal imbalances caused, those with PMOS often experience acne.
Weight gain or obesity
As with acne, the hormonal imbalances associated with PMOS frequently contribute to weight gain and obesity.
Pelvic pain
Some people with PMOS may notice pelvic pain or discomfort, which can be linked to hormonal changes and tension in the pelvic muscles.
Sleep apnea
People with PMOS, especially those who experience weight gain or suffer from obesity, are more likely to endure disordered sleep due to disrupted breathing patterns.
Anxiety or depression
Research has shown that the symptoms of PMOS such as acne, weight gain, hirsutism and infertility can negatively impact self-confidence, mood and body image – all of which can contribute to anxiety and/or depression.
How PMOS Affects the Endocrine System
PMOS (Polyendocrine Metabolic Ovarian Syndrome) isn’t just about fertility—it’s a hormonal imbalance involving your body’s endocrine system, which can have implications on other body systems.
Managing PMOS often requires addressing multiple hormone imbalances at once—through diet, lifestyle changes, or medications—to restore endocrine balance and improve overall wellbeing.
Ovaries and Hormone Imbalance
With PMOS, your ovaries don’t regularly mature and release eggs (ovulation). Instead, multiple small follicles develop but remain immature, leading to elevated production of androgens (“male” hormones such as testosterone). Irregular periods, acne, excessive hair growth, or thinning scalp hair are due to increased androgen levels, caused by the disruption of ovulation.
Insulin Resistance and PMOS
Many women with PMOS experience insulin resistance, where the body’s cells become less responsive to insulin, a hormone that regulates blood sugar. Your pancreas then compensates by producing extra insulin, which further increases androgen production by your ovaries. This cycle can worsen PMOS symptoms, cause weight gain (especially around your abdomen), and increase the risk of developing diabetes.
Broader Endocrine Impacts
PMOS affects more than just the ovaries and pancreas. It also influences hormones from your pituitary gland in the brain, often increasing LH (luteinizing hormone) levels, which further drive androgen production. Additionally, PMOS often leads to lower levels of SHBG (sex hormone-binding globulin), meaning there’s more free testosterone circulating in your body.
This hormonal imbalance explains why PMOS symptoms extend beyond fertility issues, affecting skin, hair, weight, mood, and overall metabolism.
PMOS Symptoms & Management
PMOS (Polyendocrine Metabolic Ovarian Syndrome) can cause a range of symptoms, and each woman’s experience may be different. Some women have just one or two noticeable issues, while others have multiple.
Common PMOS symptoms include:
- Irregular menstrual cycles
- Signs of high androgen levels (such as extra facial or body hair and acne)
- Weight gain or difficulty losing weight
- Multiple small follicles in the ovaries, visible on ultrasound
- Sometimes, challenges with fertility
This variability makes PMOS tricky to diagnose because not everyone has all the same symptoms.
Diagnosing PMOS
Doctors often use the Rotterdam criteria as a guide for diagnosis. According to these criteria, a PMOS diagnosis can be made if a woman has at least 2 out of 3 of the following features:
- Irregular periods or lack of ovulation: Menstrual cycles that are infrequent, irregular, or absent (indicating that ovulation isn’t happening regularly).
- Signs of high androgens: This can be clinical signs like acne or excess hair growth (hirsutism), or biochemical signs such as elevated testosterone levels on a blood test.
- Abnormal follicular development on ultrasound: An ultrasound shows the ovaries have many small follicles (previously referred to as “cysts”) arranged around the edge of the ovary. While this can be a feature of PMOS, it is not sufficient on its own for diagnosis, but counts as one of the diagnostic criteria when considered alongside other symptoms.
- More recently, a raised AMH test can also be a marker of PMOS
It’s important that other conditions are ruled out before confirming PMOS, since several disorders (like thyroid problems or elevated prolactin levels) can cause similar symptoms. Your doctor will consider your history, symptoms, and possibly do an ultrasound and blood tests to make the diagnosis.
Managing PMOS Symptoms
Polyendocrine Metabolic Ovarian Syndrome (PMOS) affects various aspects of health and often requires a combination of approaches to manage symptoms. Effective treatment can vary based on individual goals, such as improving cycle regularity, managing skin or hair symptoms, or enhancing fertility. Key strategies include:
Healthy Weight & Lifestyle
Weight management is a first-line approach for many women with PMOS. Weight gain can worsen PMOS symptoms, so maintaining a healthy weight can help balance your hormones.
If you are overweight, losing even about 5% of your body weight may lead to noticeable improvements in cycle regularity and symptom relief. However, this isn’t universal – not all women with PMOS are overweight.
Overall, a balanced diet and regular exercise improve the body’s insulin sensitivity and can reduce PMOS symptoms. Doctors often encourage lifestyle changes as the foundation of PMOS management.
Improving Insulin Resistance
Many women with PMOS have a condition called insulin resistance, where the body’s cells don’t respond well to insulin (the hormone that regulates blood sugar). This leads the body to produce extra insulin to keep blood sugar stable.
High insulin levels can trigger the ovaries to produce more androgens (male hormones), which in turn can worsen symptoms like irregular periods and hair growth.
Tackling insulin resistance can greatly improve PMOS symptoms. Doctors may prescribe medications like metformin (a medicine originally for type 2 diabetes) to help your body use insulin more effectively.
By improving the way your body processes insulin, these treatments address an underlying driver of PMOS – leading to more balanced hormones, more regular periods, and sometimes improvements in weight management and skin symptoms.
Ovulation Induction for Fertility
If getting pregnant is a goal, a common approach is ovulation induction – using medications to help the ovaries release an egg regularly. Drugs such as clomiphene citrate or letrozole are often used to stimulate ovulation.
About 75–80% of women with PMOS will ovulate with these medications, which greatly increases the chance of pregnancy in those individuals. Many patients with PMOS do conceive with the help of these ovulation medications.
If ovulation medications alone aren’t successful, the next step might be assisted reproductive technologies like IVF (in vitro fertilization). Roughly 20–25% of women with PMOS who do not respond to simpler treatments may need IVF or other advanced fertility treatments to achieve a pregnancy.
Hormonal Birth Control (Cycle Regulation)
For women who are not currently trying to get pregnant, the focus of treatment is cycle suppression in managing hormonal symptoms. The most common tool for this is the oral contraceptive pill. The pill helps to make periods regular and prevents the uterine lining from building up excessively when periods are infrequent.
In addition, birth control pills lower your body’s own testosterone levels (by increasing a hormone-binding protein), which can improve acne and reduce unwanted hair growth. Many patients find that being on the pill leads to more predictable, lighter bleeding and improvement in PMOS-related symptoms like acne.
If the OCP is not suitable for you, other methods to protect the uterus and regulate bleeding include occasional courses of a progesterone pill (to induce a bleed every few months) or a hormonal intrauterine device (IUD). These don’t fix the underlying hormone imbalance, but they ensure you have regular uterine bleeding and can help with symptoms.
Other Medications and Health Considerations
Depending on your symptoms, doctors might address other aspects of PMOS. For example, if excess hair growth is a major issue, there are specific medications or topical treatments to reduce hair. If acne is severe, dermatological treatments or certain hormonal therapies can help.
It’s also important to monitor and manage related health risks: women with PMOS, especially if overweight, have a higher risk of developing things like type 2 diabetes and high cholesterol in the long term. Your healthcare provider may check your blood sugar and cholesterol levels and recommend preventive measures (like diet changes or medications) as needed.
PMOS can also sometimes affect mood – some women experience anxiety or depression related to their symptoms or hormone fluctuations, so emotional well-being is an important part of management too.