Women's Health

PCOS: Understanding Polycystic Ovary Syndrome

A patient-focused guide to polycystic ovary syndrome (PCOS) — covering symptoms, the Rotterdam diagnostic criteria, insulin resistance, fertility, metabolic health, and treatment options.

7 min read

What Is PCOS?

Polycystic ovary syndrome (PCOS) is one of the most common hormonal conditions in women, affecting approximately 8–13% of reproductive-age women globally. Despite being widespread, it is frequently underdiagnosed, with a median delay of around 2 years from first symptoms to confirmed diagnosis.

PCOS is a syndrome, not a single disease — meaning it encompasses a spectrum of presentations united by a core set of hormonal and metabolic disturbances. It has meaningful implications across the reproductive years and beyond, affecting menstrual regularity, fertility, metabolic health, skin, hair, and psychological wellbeing.

Key Points

  • PCOS affects roughly 1 in 10 women of reproductive age; many go undiagnosed.
  • Diagnosis requires two of three Rotterdam criteria: ovulatory dysfunction, hyperandrogenism, or polycystic ovarian morphology on ultrasound.
  • You do not need to have cysts on your ovaries to have PCOS.
  • Insulin resistance is present in ~70% of women with PCOS — including those at a healthy weight.
  • PCOS is a leading cause of anovulatory infertility, but most women with PCOS can conceive.
  • Long-term cardiovascular and metabolic risks — type 2 diabetes, hypertension, dyslipidaemia — are significant and require monitoring.
  • Treatment is symptom-focused and personalised; no single approach works for everyone.

Diagnosis: The Rotterdam Criteria

PCOS is diagnosed when two of three of the following are present, and other causes have been excluded:

  1. Oligo- or anovulation — irregular or absent menstrual cycles (typically fewer than 8 cycles per year, or cycles longer than 35 days)
  2. Clinical or biochemical hyperandrogenism — excess testosterone or related hormones on a blood test, or physical signs (acne, hirsutism, androgenic alopecia)
  3. Polycystic ovarian morphology (PCOM) on ultrasound — 12 or more antral follicles in at least one ovary, or increased ovarian volume; note that this criterion has limited value in adolescents

Conditions to exclude before diagnosing PCOS:

  • Thyroid dysfunction (TSH)
  • Hyperprolactinaemia (prolactin)
  • Congenital adrenal hyperplasia (17-OHP if indicated)
  • Androgen-secreting tumours (if rapid-onset virilisation is present)

A diagnosis of PCOS based on Rotterdam criteria has distinct “phenotypes” with varying severity of metabolic and reproductive features. Women with hyperandrogenism tend to have the most pronounced metabolic risk.

Insulin Resistance and Metabolic Health

Insulin resistance is a core — though often underappreciated — feature of PCOS, present in approximately 70% of affected women, regardless of weight. In insulin-resistant states:

  • Elevated circulating insulin stimulates ovarian theca cells to produce excess androgens (testosterone and androstenedione)
  • Insulin suppresses sex hormone-binding globulin (SHBG) production, increasing the proportion of free (active) androgens
  • Compensatory hyperinsulinaemia worsens the androgen excess, creating a self-reinforcing cycle

Metabolic consequences:

RiskMagnitude
Type 2 diabetes3–7× increased lifetime risk
Impaired fasting glucose or prediabetesCommon, even in lean women
Metabolic syndrome2–3× more prevalent
Non-alcoholic fatty liver diseaseElevated risk
DyslipidaemiaIncreased triglycerides, low HDL

Insulin resistance contributes substantially to the cardiovascular risk profile of PCOS, independent of obesity.

Reproductive Features

Irregular Periods

Oligo/anovulation is the defining reproductive feature. It results in irregular, infrequent, or absent menstrual bleeding. Paradoxically, periods — when they do occur — can be heavy, as prolonged anovulatory intervals allow the uterine lining to thicken without the regular shedding that ovulation-driven progesterone would provide.

Fertility

PCOS is among the leading causes of anovulatory infertility. However, most women with PCOS do conceive. Options include:

  • Lifestyle modification — weight loss of 5–10% in overweight women can restore ovulation
  • Letrozole — first-line ovulation induction agent; superior to clomiphene in PCOS
  • Clomiphene citrate — established option; slightly lower live birth rates than letrozole in PCOS
  • Metformin — improves ovulatory response, often used in combination with letrozole
  • Laparoscopic ovarian drilling — surgical option if medication is ineffective
  • IVF — for complex cases or failed ovulation induction

Women with PCOS undergoing IVF face elevated risk of ovarian hyperstimulation syndrome (OHSS); careful ovarian stimulation protocols are required.

Hyperandrogenic Features

Elevated androgens drive several clinical features that bring women with PCOS to medical attention:

  • Hirsutism — excess terminal hair growth in a male pattern (upper lip, chin, chest, abdomen); affects 65–75% of women with biochemical hyperandrogenism
  • Acne — often persistent, comedonal, and cystic, particularly on the jaw and chin
  • Androgenic alopecia — diffuse thinning at the crown; distressing but often underrecognised as a PCOS manifestation
  • Seborrhoea — oily skin

These symptoms can have a substantial impact on self-esteem and mental health, and are often dismissed or undertreated.

Mental Health

Women with PCOS have significantly elevated rates of:

  • Depression — approximately twice as common as in age-matched controls
  • Anxiety disorders
  • Disordered eating and body image concerns
  • Reduced quality of life

These associations are partially attributable to the psychological burden of symptoms (hair, skin, weight changes) and the impact of fertility concerns, but there may also be independent biological pathways. Psychological support should be considered an integral part of PCOS management, not an afterthought.

Treatment

PCOS is a lifelong condition; treatment is symptom-focused and personalised. No intervention cures PCOS.

Lifestyle

For overweight women with PCOS, 5–10% weight loss improves insulin sensitivity, reduces androgen levels, restores cycles, and improves reproductive and metabolic outcomes. Diet quality matters as much as caloric restriction — low-glycaemic-index diets and Mediterranean-style dietary patterns are well supported. Regular physical activity improves insulin sensitivity independently of weight change.

For women at a healthy weight, lifestyle interventions focus on diet quality, physical activity, and avoiding excessive caloric restriction.

Metformin

Metformin reduces hepatic glucose production and improves peripheral insulin sensitivity. In PCOS:

  • Reduces androgen levels
  • May restore menstrual regularity
  • Supports ovulation induction
  • Reduces progression to type 2 diabetes
  • Modest effect on weight

Not all women with PCOS tolerate or benefit from metformin; it is most effective in those with significant insulin resistance or elevated glucose.

Oral Contraceptive Pill (OCP)

The combined OCP regulates cycles and reduces androgen-driven symptoms by:

  • Suppressing LH-driven ovarian androgen production
  • Increasing SHBG, which binds free testosterone

Preparations with anti-androgenic progestogens (e.g., drospirenone, cyproterone acetate) may be preferred for hirsutism and acne. The OCP does not treat the underlying PCOS and symptoms typically return on discontinuation.

Anti-Androgens

  • Spironolactone — reduces hirsutism and acne; requires contraception (teratogenic)
  • Cyproterone acetate — potent anti-androgen; used for severe hirsutism or acne
  • Flutamide, finasteride — used in some settings; require contraception

Ovulation Induction

See the fertility section above. Letrozole is now the preferred first-line agent, with metformin as a common adjunct.

Long-Term Monitoring

Given the metabolic risk profile of PCOS, regular monitoring is recommended even in the absence of current symptoms:

  • Blood glucose / HbA1c — every 1–2 years
  • Lipid profile — baseline and periodically
  • Blood pressure — at every clinical visit
  • Mental health screen — at diagnosis and periodically
  • Endometrial surveillance — in women with prolonged anovulation, the risk of endometrial hyperplasia (and, rarely, endometrial cancer) is elevated; if no period for > 3–6 months, progestogen-induced withdrawal bleed or OCP use is recommended

Further Reading

Last updated: May 2026