PCOS 101: Signs, Causes, and How It Affects Fertility

Polycystic ovary syndrome, or PCOS, is one of the most common hormonal conditions among women of reproductive age — yet it's also one of the most misunderstood. If you've recently been told you might have PCOS, or you suspect you do, this guide walks through what it actually is, what causes it, and what it can mean for your fertility.

What is PCOS?

PCOS is a hormonal condition typically involving some combination of three features: irregular or absent ovulation, higher-than-typical levels of androgens (sometimes called "male hormones," though everyone has them), and ovaries containing many small, fluid-filled follicles that haven't fully matured. Most healthcare providers diagnose PCOS when a woman has at least two of these three features, after other conditions have been ruled out.

Despite the name, "polycystic" ovaries are not the same as ovarian cysts in the way many people picture them — they're small, immature follicles rather than large fluid-filled growths.

Common signs of PCOS

• Irregular, infrequent, or absent periods.
• Acne, especially along the jawline, or oily skin.
• Excess hair growth on the face, chest, or back (hirsutism).
• Thinning hair on the scalp.
• Weight gain or difficulty losing weight, particularly around the abdomen.
• Difficulty conceiving due to irregular or absent ovulation.
• Skin changes such as darkened patches of skin (acanthosis nigricans).

Not every woman with PCOS experiences every sign, and severity varies widely from person to person.

What causes PCOS?

The exact cause of PCOS isn't fully understood, but research points to a combination of factors that often overlap:

Insulin resistance

Many women with PCOS have some degree of insulin resistance, meaning the body needs more insulin to manage blood sugar. Higher insulin levels can, in turn, encourage the ovaries to produce more androgens.

Genetics

PCOS tends to run in families, suggesting a genetic component, though no single gene has been identified as "the" cause.

Low-grade inflammation

Some studies associate PCOS with chronic low-grade inflammation, which may also stimulate androgen production by the ovaries.

How PCOS affects fertility

PCOS is one of the most common causes of ovulation-related infertility. When ovulation is irregular or absent, there are fewer or no opportunities for conception each cycle. This doesn't mean pregnancy is impossible — many women with PCOS do conceive naturally, sometimes with support to help regulate ovulation and cycle timing.

PCOS is about more than fertility

PCOS often comes up first when periods go missing or pregnancy takes a while. But it's a whole-body hormonal pattern, so it helps to look after your long-term health too. Women with PCOS have a higher chance of:

• Prediabetes and type 2 diabetes, linked to insulin resistance. Regular blood sugar checks can catch changes early.
• Higher cholesterol and blood pressure, which are worth checking from time to time.
• Sleep apnea, where breathing pauses during sleep. Loud snoring and daytime tiredness are clues.
• Anxiety and low mood. These are common and real, and they deserve care just as much as physical symptoms.
• Changes in the uterine lining if periods are very infrequent for a long time, since the lining isn't shedding regularly.

Hearing this list can feel heavy. The good news is that the same everyday habits that support your cycle also support these areas, and simple check-ups help you stay a step ahead. If weight is part of your experience, our guide to PCOS belly and weight explains the link with insulin.

How PCOS is typically diagnosed

Diagnosis usually involves a combination of a symptom and cycle history review, blood tests to check hormone levels, and a pelvic ultrasound to look at the ovaries. Because several conditions can mimic PCOS symptoms, a proper evaluation matters more than self-diagnosis based on symptoms alone.

Conditions that can look like PCOS

Irregular periods, acne and extra hair growth have more than one possible cause. Before confirming PCOS, a provider will usually rule out a few look-alikes with simple blood tests:

• Thyroid problems, which can change cycle length and energy levels.
• High prolactin, a hormone that can pause ovulation when it's raised.
• Adrenal gland conditions, which can also raise androgen levels.
• Hypothalamic amenorrhea, where periods stop because of low energy intake, intense exercise or heavy stress.

It also helps to know that "polycystic" ovaries on an ultrasound are different from the larger cysts covered in our guide to ovarian cyst symptoms.

Myths vs facts about PCOS

• Myth: You need cysts on your ovaries to have PCOS. Fact: Ovary findings on ultrasound are only one of three features. Many women are diagnosed without them.
• Myth: PCOS only affects women with a larger body. Fact: PCOS happens at every size, including in women with a lean build.
• Myth: PCOS goes away once you're on birth control. Fact: Birth control can help manage some symptoms, but the underlying hormone pattern is still there.
• Myth: Nothing can be done. Fact: PCOS is very manageable. Lifestyle support and options a doctor may discuss can make a real difference to how you feel.

Questions to ask your provider

• Which of the three PCOS features do I have, and how was each one checked?
• Have thyroid problems, high prolactin and other look-alike conditions been ruled out?
• Should my blood sugar and cholesterol be checked, and how often?
• How often should I have a period to protect my uterine lining?
• If I want to get pregnant now or later, what should my next steps be?

Supportive steps that may help

• A balanced, consistent diet that supports stable blood sugar levels.
• Regular movement, which may help support insulin sensitivity over time.
• Consistent sleep and stress management.
• Targeted nutritional support formulated with PCOS-related needs in mind.
• Working with a healthcare professional on a plan tailored to your specific pattern of symptoms.

AGO Women and AGO Mom are formulated to help support hormonal balance as part of a broader PCOS-friendly care routine — alongside, not instead of, medical guidance.