Poor ovarian response classification systems in the clinical setting – time for an update?

Purpose of review Poor ovarian response (POR) remains a key challenge to the success of assisted reproductive technology. Here, we offer a comprehensive review of the two main classification systems for POR, discussing their promises and pitfalls, evaluating their performance, and exploring potential avenues for improving upon these definitions of POR. Recent findings The Bologna criteria represented the first meaningful attempt to create a universal POR definition. Subsequently, the POSEIDON classification system was published to provide a more nuanced view of POR, classifying patients into four groups based on age and ovarian reserve markers. A recent study evaluated the likelihood of achieving at least one euploid embryo for transfer and found that, indeed, these classification systems are effective predictors of this outcome. While these criteria provide an effective counseling tool, several limitations – not considering underlying conditions, selecting somewhat arbitrary cutoffs, and evaluating the number of oocytes retrieved regardless of maturity – highlight the importance of improving upon these systems to create a more useful tool to more accurately predict ovarian response for clinical and research purposes. Summary In the era of personalized medicine, it is time to reconsider whether diagnostic criteria for a continuous metric such as ovarian response should be based on meeting all-or-nothing thresholds for specific parameters.