Another round, another chance: oocyte developmental competence and outcomes in second IVF attempts-the earlier, the better

Purpose: To evaluate whether the outcomes and characteristics of a first IVF/ICSI cycle are associated with embryological and clinical outcomes in a subsequent cycle performed within 2 years. Methods: This retrospective single-center observational study included 1190 couples undergoing two stimulated ICSI cycles with planned blastocyst culture between 2015 and 2020. Associations between first- and second-cycle outcomes were analyzed, including oocyte yield, blastocyst development, and live birth. The effect of the inter-cycle interval was assessed using multivariate models. Results: The mean maternal age was 38.7 years, and the mean AMH level was 1.7 ng/ml. Second cycles showed improved embryological outcomes, including higher numbers of retrieved cumulus-oocyte complexes (COCs), increased blastocyst yield, and higher blastocyst rate per COC. Overall, 50% of patients retrieved more COCs in the second cycle, and 87% of those with no COCs in the first cycle obtained ≥ 1 in the second. A longer inter-cycle interval was negatively associated with outcomes, reducing the likelihood of retrieving more COCs (OR 0.96 per month, 95% CI 0.93-0.98), obtaining more blastocysts (OR 0.95, 95% CI 0.93-0.98), and improving blastocyst rate (OR 0.96, 95% CI 0.94-0.99). First-cycle outcomes were not associated with live birth probability in the second cycle, which was instead associated with maternal age and the number of COCs previously retrieved. Conclusions: First-cycle outcomes should not discourage further attempts, as subsequent cycles may yield improved embryological results. A shorter interval between cycles represents a modifiable factor associated with better outcomes. These findings support early re-treatment and a multicycle counseling approach to optimize cumulative live birth rates, especially as maternal age and ovarian reserve remain the most important predictors of success even in second attempts.