Polycystic ovary syndrome, or PCOS, is one of the most common hormonal conditions affecting women of reproductive age. In May 2026, an international consensus of 56 medical and patient organizations, published in The Lancet, renamed the condition polyendocrine metabolic ovarian syndrome (PMOS) to better reflect its hormonal and metabolic scope beyond the ovaries. The condition itself hasn’t changed, and most people and healthcare providers still use PCOS while the new terminology takes hold, so we use PCOS throughout this article.
Regardless of what it’s called, the underlying condition works the same way: a hormonal imbalance disrupts how the ovaries function. Women with PCOS often produce higher levels of androgens, or male hormones, than typical, which can prevent regular ovulation. This can lead to irregular periods, difficulty getting pregnant, and a range of symptoms affecting the skin, hair, and metabolism.
PCOS affects an estimated 8 to 13% of women of reproductive age, according to the American Society for Reproductive Medicine (ASRM). It’s the most common cause of female infertility. Despite how common it is, the World Health Organization estimates that up to 70% of women with PCOS remain undiagnosed worldwide. If you suspect you have PCOS or have recently been diagnosed, understanding the condition is the first step toward finding the right treatment path, whether that means lifestyle changes, fertility medication, or IVF.
Key Takeaways
What Causes PCOS?
The exact cause of PCOS isn’t fully understood, but research points to a few overlapping factors.
Insulin Resistance
Many women with PCOS have insulin resistance, meaning their bodies don’t respond normally to insulin, the hormone that regulates blood sugar. When cells resist insulin’s effects, the pancreas produces more of it to compensate. Elevated insulin levels can prompt the ovaries to produce more androgens, which disrupts ovulation. Insulin resistance is also linked to weight gain and a higher long-term risk of type 2 diabetes in women with PCOS.
Excess Androgens
That rise in androgens is central to PCOS. Higher-than-typical androgen levels can prevent the ovaries from releasing a mature egg each month and are also responsible for physical symptoms like excess hair growth and acne.
Genetics and Family History
The overlap between insulin resistance and androgen production may itself be genetically influenced. PCOS tends to run in families – if your mother or sister has PCOS, you have a higher likelihood of developing it too, though no single gene has been identified as the cause.
PCOS Symptoms
PCOS symptoms vary widely from person to person, and some women have very mild symptoms while others experience more pronounced effects.
Types of PCOS (PCOS Phenotypes)
Diagnosis is based on meeting 2 of 3 criteria, which means there are several recognized phenotypes, or subtypes, of PCOS:
| Phenotype | Irregular Ovulation | Excess Androgens | Polycystic Ovaries |
|---|---|---|---|
| Type A (Classic PCOS) | ✓ | ✓ | ✓ |
| Type B | ✓ | ✓ | — |
| Type C (Ovulatory PCOS) | — | ✓ | ✓ |
| Type D (Non-Hyperandrogenic PCOS) | ✓ | — | ✓ |
Type A tends to carry the most pronounced metabolic and fertility effects, while Type D often presents with milder symptoms. Knowing your phenotype can help your fertility specialist tailor a more precise treatment plan. Whichever phenotype you have, diagnosis follows the same basic process.
PCOS Diagnosis: How Doctors Test For It
There’s no single test for PCOS. Instead, doctors use the Rotterdam criteria, which require meeting at least two of the following three conditions:
- Irregular or absent ovulation, reflected in irregular or missing periods
- Signs of excess androgens, either physical (hirsutism, acne) or confirmed through a blood test
- Polycystic ovaries on ultrasound, showing multiple small follicles around the edge of the ovary
A typical diagnostic workup includes:
Because PCOS symptoms can overlap with other conditions, your doctor may also run additional tests to rule out thyroid disorders or other hormonal imbalances before confirming a diagnosis. Once PCOS is confirmed, addressing its effect on fertility is often the next priority for women trying to conceive.
PCOS and Infertility
One of the most common questions after a diagnosis is whether PCOS causes infertility. PCOS is the leading cause of anovulatory infertility, meaning infertility caused by a lack of regular ovulation. Without consistent ovulation, the ovaries don’t reliably release a mature egg each month, making it harder to conceive without medical support.
PCOS and Pregnancy Complications
Women with PCOS who become pregnant may face a higher risk of certain complications, including gestational diabetes, preeclampsia, preterm birth, and early pregnancy loss. This doesn’t mean complications are guaranteed. Many women with PCOS carry healthy pregnancies to term, especially with proper monitoring and care.
Long-Term Health Risks of PCOS
PCOS’s effects aren’t limited to fertility. Because insulin resistance and excess androgens affect the whole body, PCOS is also linked to a higher long-term risk of: conceive, and it’s part of why an accurate, early diagnosis matters as much as fertility treatment itself.
These risks are one of the reasons doctors recommend ongoing monitoring, even for women who aren’t currently trying to conceive, and it’s part of why an accurate, early diagnosis matters as much as fertility treatment itself.
PCOS Treatment Options
Treatment for PCOS, whether the goal is symptom management or pregnancy, typically follows a step-up approach that starts with the least invasive options.
Lifestyle Changes
For women who are overweight, losing even 5% of body weight can be enough to restore regular ovulation in some cases. Diet and exercise changes are typically recommended as a first step. Small, targeted changes can help – for example, research on meal timing suggests that women with PCOS who eat more of their daily calories earlier in the day see measurable drops in insulin and testosterone levels.
Fertility Medications
If lifestyle changes alone aren’t enough after three to six months, fertility medications are often the next step:
Letrozole is now generally recommended as the first-line medication for ovulation induction in women with PCOS, as it’s associated with higher ovulation and live birth rates compared to older treatments.
Clomiphene (Clomid) works by blocking estrogen receptors, which prompts the body to produce more follicle-stimulating hormone (FSH) to mature a follicle. It remains a common alternative to letrozole, though it carries a slightly higher chance of multiple births. See our comparison of letrozole vs. Clomid for more on how doctors choose between them.
Gonadotropins are injectable hormones used when oral medications don’t produce ovulation. They require closer monitoring due to a higher risk of multiple pregnancies and ovarian hyperstimulation.
As with any fertility medication, it’s worth understanding the full range of possible side effects before starting treatment. For some women, intrauterine insemination (IUI) is tried before moving to IVF, particularly when PCOS-related infertility is mild, and ovulation can be reliably induced with medication alone.
IVF for PCOS-Related Infertility
When medication and IUI don’t lead to pregnancy, IVF is often the next step. IVF gives your fertility team more control over the stimulation process, which matters for women with PCOS, since their ovaries tend to respond more strongly to fertility medications.
A carefully managed protocol can reduce the risk of ovarian hyperstimulation while still maximizing the number of healthy eggs retrieved – something our PCOS and IVF guide covers in more detail, including OHSS risk and how often you’ll be monitored.
For the broader mechanics of a cycle, check out how the complete IVF process works at each stage, from stimulation through transfer.
Frequently Asked Questions
Conclusion
PCOS, now recognized under its updated name PMOS, is one of the most common and most treatable causes of infertility. Understanding your specific symptoms, phenotype, and long-term health risks gives you and your fertility team the clearest path toward a treatment plan that fits your body and your goals.
Ready to Talk to a Fertility Specialist About PCOS?
If you suspect you have PCOS or have already been diagnosed and are ready to explore your fertility options, our team at RSMC can help you build a personalized treatment plan.
