How should IVF protocols be optimised in women with PCOS to maximise success while minimising OHSS risk?

[Terminology: PCOS was renamed polyendocrine metabolic ovarian syndrome (PMOS) by global consensus in May 2026, published in The Lancet. The International Guideline now uses PMOS/PCOS in its recommendations and will use PMOS alone from 2028. Clinical content, diagnostic criteria and management are unchanged.]

ESHRE (2026) recommendations relevant to PCOS and predicted high response: Protocol and dose. The GnRH antagonist protocol is recommended for predicted high responders (strong). A reduced gonadotropin dose of 100 to under 150 IU is probably recommended to decrease OHSS risk (conditional). Delayed-start stimulation is probably not recommended routinely in predicted high responders to decrease OHSS risk (conditional). Adjuvants — note these are recommendations against. Routine metformin before or during stimulation is probably not recommended when using the antagonist protocol in women with PCOS (conditional). Growth hormone is not recommended for women with PCOS (strong). Myo-inositol is probably not recommended for women with PCOS undergoing IVF (conditional). Adding letrozole to gonadotropins is probably not recommended in predicted high responders (conditional). OHSS prevention. A GnRH agonist trigger combined with freeze-all is recommended to minimise severe OHSS risk (strong). Dopamine agonists are recommended to decrease early OHSS risk, particularly where hCG is used for final maturation (strong, 2025). A freeze-all strategy is recommended to minimise late-onset OHSS (strong). In agonist cycles with 19 or more follicles of 11 mm or greater, preventative measures are recommended, primarily cancelling the trigger (strong). Adding hCG to a GnRH agonist as a dual trigger is probably not recommended in high responders (conditional).