Polyendocrine metabolic ovarian syndrome (PMOS)
Formerly known as polycystic ovary syndrome (PCOS)
Polyendocrine metabolic ovarian syndrome (PMOS), formerly known as PCOS, is caused by a combination of hormonal, genetic, and metabolic factors that can lead infrequent or absent ovulation — the body’s process of producing and releasing eggs from the ovary.
Essentially, people with PMOS have an inappropriate production of androgens and testosterone, that can delay or prevent ovulation. People with PMOS also typically have abnormal glucose regulation due to insulin resistance, which worsens ovarian function, increases androgens, and can lead to obesity.
Schedule an AppointmentEffective May 2026, polycystic ovary syndrome (PCOS) has been renamed polyendocrine metabolic ovarian syndrome (PMOS). The new name more accurately reflects the hormonal and metabolic nature of the condition. You may still see “PCOS” in older materials — it refers to the same condition.
What is PMOS?
PMOS stands for polyendocrine metabolic ovarian syndrome (PMOS). It’s a hormonal and metabolic condition that disrupts ovulation and hormone balance. Many people with PMOS can have excessive ovarian follicles as well. This is called polycystic ovary and it is not dangerous. Common symptoms or signs include:
- Irregular menstrual periods or ovulations
- Heightened levels of male hormones (testosterone), which result in excess facial and body hair and/or acne
- Finding of polycystic ovary on ultrasound
Why was PCOS renamed to PMOS?
PCOS was renamed because the old name didn’t fully capture the condition. Many people diagnosed with PCOS don’t have polycystic ovaries, and some people with polycystic ovaries don’t have PCOS at all. The new name, polyendocrine metabolic ovarian syndrome, refocuses the diagnosis on what’s important: multiple hormone systems (polyendocrine), metabolic changes like insulin resistance (metabolic), and effects on the ovaries (ovarian).
What causes PMOS/PCOS?
The cause of PMOS/PCOS is not completely understood. It is clear that there is a genetic basis to the condition, as a person is more likely to develop the condition if their immediate family member has it. It is also known that disrupted signaling from the brain to the ovary affects ovarian hormone production, which further exacerbates, or worsens, the condition.
High androgen levels and high insulin levels may also contribute to the condition, creating a cycle that can make symptoms harder to manage.
Symptoms of PMOS
The hormonal imbalances experienced by people with PMOS can cause the following symptoms:
- Irregular menstrual cycles, specifically those that are 3 to 5 days shorter or longer than a typical cycle (a normal cycle ranges between 21 and 35 days).
- Heavy or absent periods — some women with PMOS only menstruate one to two times a year.
- Acne.
- Excess facial and body hair.
- Weight gain or difficulty losing weight
- Thinning hair or hair loss on the scalp
- Oily skin
- Elevated testosterone levels
How PMOS affects fertility
PMOS is a leading cause of female infertility, yet many women with the condition go on to conceive and have healthy pregnancies. The impact of PCOS on fertility can include:
- Irregular or absent ovulation caused by hormonal imbalances
- Difficulty with implantation or early pregnancy loss
- Insulin resistance, which can affect egg quality and hormone balance
- Chronic low-grade inflammation, which may make it harder for an embryo to implant
People with PMOS often benefit from early evaluation and management. Consulting a fertility specialist can provide personalized treatment options to support your reproductive goals. Meet RSC’s physicians to find the right fit for your care.
Diagnosing PMOS
Your medical history and a pelvic exam are necessary for diagnosing PMOS. However, your physician may need other tests to confirm the diagnosis such as:
- Blood hormone levels: Blood tests that reveal the levels of certain hormones in your blood, such as FSH, LH, estrogen (estradiol), and androgens like testosterone.
- Ultrasound: An imaging scan that uses high-frequency sound waves to identify cysts in the ovaries.
Are there long-term risks or health problems linked to PMOS?
Long-term exposure to high estrogen levels without enough progesterone to balance it can thicken the lining of the uterus over time, which raises the risk of endometrial (uterine) cancer. Because irregular ovulation with PMOS means the uterine lining isn’t shed as regularly, this is something to manage over time, not just monitor. Hormonal birth control that contains progesterone, like the oral contraceptive pills or a progesterone containing IUD, can help regulate the menstrual cycle and lower this risk. Your doctor can help you find the right option for your health and family-building goals.
PMOS is also linked to a higher likelihood of other health conditions, so your doctor may recommend additional screening over time, including:
- Diabetes
- High blood pressure
- Unhealthy cholestorol
- Sleep problems
- Depression and anxiety
- Endometrial cancer
Fertility treatment options for PCOS/PMOS
Your fertility treatment for PMOS will depend on your specific needs. Carrying excess weight can make PMOS symptoms harder to manage, and even modest weight loss may help improve hormonal balance. If your goal is to become pregnant, your doctor may prescribe a medication to stimulate ovulation. Common fertility treatments include oral medications to help with ovulation such as clomiphene citrate (Clomid, Serophene) and letrozole (Femara). Your doctor may prescribe a second oral diabetic medicine, such as metformin, which can help make the body more sensitive to insulin and lead to more regular ovulation.
Historically, Clomid had been the first line of treatment for PMOS. Currently, letrozole is considered the standard because it has been proven to offer a higher chance of pregnancy. Your doctor can help determine which option is right for you. It’s important to note that if you haven’t conceived after three to four cycles of ovulation induction, you should consider a different course of treatment, such as intrauterine insemination (IUI) or in vitro fertilization (IVF).
Lifestyle changes, such as eating a balanced diet and staying active, can greatly help reduce bothersome PMOS symptoms alongside medical treatment. Over the counter supplements like inositol or prescription medication like Metformin help to lower insulin resistance and stabilize irregular cycles, even before starting ovulation-stimulating medication.
For individuals who aren’t actively trying to conceive
An early PMOS diagnosis matters, even if pregnancy isn’t part of your plans right now. PMOS affects more than fertility. It’s tied to metabolic health, hormone balance, and long-term wellbeing. Without a diagnosis, related health issues like insulin resistance, irregular ovulation, and metabolic changes can go unaddressed for years. Getting evaluated early gives you and your doctor more time to manage these issues before they become harder to treat. It also means you’ll have a clearer picture of your reproductive health if you decide to grow your family.
Take control of your fertility journey
PMOS/PCOS doesn’t have to stand in the way of your dreams of parenthood. At RSC, we’re committed to helping you understand your condition, explore your options, and take confident steps forward.
