PCOS: What It Is and How It Affects Pregnancy

Polycystic ovary syndrome (PCOS) is diagnosed in around 10% of women of reproductive age — and it is one of the leading reasons people seek help from a fertility specialist. Despite this, PCOS is significantly underdiagnosed: estimates suggest that up to 70% of cases go unrecognised. Many people only learn about the syndrome when they encounter difficulty conceiving. Despite its name, 'polycystic' doesn't mean what most people imagine. 'Poly' plus 'cystis' means 'many vesicles' — referring to antral follicles, which are present in abnormally high numbers in PCOS ovaries. They don't grow to the required size and don't rupture — meaning ovulation either doesn't occur or happens irregularly. This is the root of the difficulty with conception.

What happens in PCOS: the mechanism

At the core of PCOS is a disruption in hormone regulation, though the underlying causes are not fully understood. The key components: excess androgens (male sex hormones — testosterone and its precursors); insulin resistance (cells respond poorly to insulin, the pancreas produces more, and the excess insulin further stimulates the ovaries to produce androgens); and an abnormal LH-to-FSH ratio (in PCOS, LH is chronically elevated relative to FSH, disrupting normal follicle maturation). A fascinating detail: PCOS is not strictly an 'ovarian disease' — it is a systemic hormonal-metabolic syndrome in which the ovaries are simultaneously a victim of the hormonal imbalance and a source of it. This is why PCOS is associated with elevated risks of type 2 diabetes, cardiovascular disease and metabolic syndrome — independently of fertility.

Symptoms: what should raise concern

Irregular menstrual cycle — the most common symptom. A cycle longer than 35 days, infrequent periods (oligomenorrhoea) or their complete absence (amenorrhoea) may all indicate PCOS. An irregular cycle means irregular — or absent — ovulation. Signs of hyperandrogenism: acne (especially on the chin and lower face), excess hair growth on the face, chest, abdomen or thighs (hirsutism), and male-pattern hair loss on the scalp. All of these result from excess androgens. Enlarged ovaries with a high follicle count on ultrasound. This is the 'polycystic' appearance — but on its own, without other features, it is not a diagnosis. Under current Rotterdam criteria (2003), a PCOS diagnosis requires at least two of three findings: ovulatory dysfunction, hyperandrogenism, and polycystic ovarian morphology. Difficulty losing weight. Insulin resistance makes weight loss harder and promotes abdominal fat deposition. Excess weight in turn worsens PCOS — a vicious cycle.

Diagnosis: what the workup includes

PCOS is diagnosed on the basis of a combination of findings — after excluding other conditions that produce a similar picture: congenital adrenal hyperplasia, hyperprolactinaemia, thyroid dysfunction. Standard workup includes: blood tests for hormones (LH, FSH, free and total testosterone, DHEA-S, prolactin, TSH); insulin and glucose testing (insulin resistance assessment); pelvic ultrasound (antral follicle count and ovarian volume assessment). Important: in PCOS, AMH is often substantially elevated — sometimes several times the upper limit of normal. This reflects the excess number of follicles, not good functional ovarian reserve. A high AMH in PCOS should not be confused with high fertility.

PCOS and pregnancy: what you need to know

PCOS is the most common cause of anovulatory infertility — but it does not mean pregnancy is impossible. Many women with PCOS conceive, both naturally and with medical assistance. The treatment spectrum is broad: from lifestyle modification to IVF. Weight loss (even 5 to 10% of baseline weight) in overweight women with PCOS frequently restores ovulation and regular cycles without any other treatment. This is the most effective non-pharmacological intervention when applicable. Ovulation induction. First-line agents are letrozole (currently preferred over clomiphene based on evidence) or clomiphene citrate. If these are ineffective: gonadotrophins or surgical induction (laparoscopic ovarian drilling). IVF is used when other methods have failed or additional factors are present (male factor, tubal factor). In PCOS, the risk of ovarian hyperstimulation syndrome (OHSS) during IVF is higher — which is why mild protocols and a freeze-all strategy are used to minimise risk. Metformin — a type 2 diabetes drug — is sometimes prescribed in PCOS to reduce insulin resistance. It can improve cycle regularity and reduce the risk of OHSS during IVF. It is not a first-line conception drug but is used as adjunctive therapy.

PCOS during pregnancy: elevated risks

Even after achieving pregnancy, PCOS remains clinically significant. Women with PCOS have higher risks of gestational diabetes, pre-eclampsia, preterm birth and caesarean section. These risks require closer monitoring throughout pregnancy.

The bottom line

PCOS is not a verdict — it is a manageable condition. It does not automatically mean infertility. It does not resolve by itself with age, though some symptoms may change. It requires a long-term approach: not only to fertility but to metabolic health overall. If you have an irregular cycle, signs of hyperandrogenism or difficulty conceiving — these are sufficient grounds for a workup. PCOS responds well to the right treatment, and most women with the syndrome ultimately achieve the pregnancy they are hoping for.