Received August 28, 2025
Accepted June 05, 2026

Objective: This study aims to compare the effect of using fresh ejaculated sperm versus cryopreserved sperm on the morphology and kinetics of embryo development and on clinical reproductive outcomes. Methods: Retrospective, observational, single-centre study conducted at IVIRMA Alicante (June 2013-December 2020) that included 469 oocyte donation cycles with frozen, fresh and mixed eggs in which ICSI, IVF or IVF-ICSI with fresh ejaculated and frozen ejaculted partner sperm was performed. For each group, the morphokinetic variables t2, t3, t4, t5, t6, t7, t8, tM, tSB, tB, tEB were studied in addition to the clinical gestation rate, implantation rate, ongoing pregnancy rate, miscarriage rate, and live birth rate, per transfer and per embryo transferred. Statistical analysis was performed with IBM SPSS® software. Values of p≤0.05 were considered statistically significant. Results: Longer development times were observed in the fresh semen group, with significantly longer times for t2, t3, t4, t5, tB, tEB. Clinical results per transfer showed a trend, although not significant, to lower rates in the cryopreserved semen group compared to the fresh semen group. However the miscarriage rate was higher for the cryopreserved semen group, but not significant. Conclusion: Our results indicate that embryos from fresh semen have a slower developmental speed for the morphokinetic parameters studied. Since no significant differences in clinical reproductive outcomes were found, it is concluded that sperm freezing is a valuable technique that can continue to be applied. However, further studies are needed to confirm these results.