The clinical scale of PCOS — 8-13% of women of reproductive age globally, up to 20-25% in some ethnic groups — and the role of elevated LH in driving the syndrome and complicating stimulation. The 2023 international PCOS guideline, the revised Rotterdam criteria, and a real-world look at NHSU caseload showing how often PCOS sits behind anovulatory infertility.
PCOS accounts for around 70% of anovulatory infertility cases. Elevated LH is both a diagnostic marker and a driver of theca-cell hyperandrogenism. Stimulation pitfalls in PCOS — premature LH surge, OHSS risk, asynchronous follicular growth — are largely predictable from baseline LH and ovarian morphology. The 2023 guideline reframes diagnosis and management around the revised Rotterdam criteria with stricter ultrasound thresholds.
Lock the diagnosis using the revised Rotterdam criteria before designing the protocol. Choose an antagonist protocol with low-dose start and individualised trigger for PCOS to manage OHSS risk while preserving oocyte maturation. Combine inositol, metformin and lifestyle where indicated; treat LH excess as a parameter to manage, not to ignore.
Rotterdam ultrasound thresholds have changed — older diagnoses may need revisiting. LH levels in PCOS are not always elevated; phenotype A, B, C, D behave differently. PCOS is heterogeneous; one stimulation protocol does not fit all four phenotypes.
PCOS affects 8-13% of women of reproductive age and drives 70% of anovulatory infertility. A look at the role of elevated LH in PCOS pathogenesis, the 2023 international guideline, the revised Rotterdam criteria — and what a personalised stimulation pathway looks like in 2026.
