POSEIDON criteria revisited

Peter Humaidan draws a ten-year balance of the POSEIDON classification and looks ahead — what it changed in the approach to "difficult" patients and where stimulation personalisation is heading.

POSEIDON's chief achievement is the move from the blurred label "poor responder" to stratifying low-prognosis patients into clear groups. It is built on age, the number of retrieved oocytes and reserve markers (AMH, antral follicle count), letting us speak not of a "bad patient" in general but of a specific subgroup with a defined strategy.

The key divide is age 35. It matters chiefly because of the molecular mechanisms shaping an embryo's chromosomal make-up: oocyte biology differs before and after this threshold. Hence the practical rule captured in the quote: "Whenever a patient is 35 and above, we start LH from day one."

A separate thought is the role of receptor polymorphisms. The speaker's conceptual remark — "if we had known the FSH receptor, LH receptor polymorphisms" — points the way: pharmacogenomics can explain an unexpected hypo-response in advance and guide drug and dose choice even before the first stimulation.

Humaidan proposes considering POSEIDON and APHRODITE together, in one clinical context: female and male stratification cease to be parallel worlds and combine into a single picture of the couple.

Hence the overarching idea: infertility is a couple's problem, not a single patient's. Work-up and strategy must cover both partners at once, or efforts to optimise the female protocol may founder on an unaddressed male factor — and vice versa.

The dosing implications follow from the POSEIDON group: sometimes the priority is not to lose time and to add LH from the start; sometimes it is the gentlest possible stimulation with protection from hyper-response. The classification helps avoid "treating everyone the same."