FLEXIBLE PROGESTIN-PRIMED VERSUS ANTAGONIST PROTOCOL: COMPARISION OF CLINICAL OUTCOME AND EMBRYO MORPHOKINETICS

For luteinizing hormone (LH) suppression in controlled ovarian stimulation, the GnRH antagonist protocol remains the gold standard but requires multiple injections and high therapeutic costs. Progestin-primed ovarian stimulation (PPOS), particularly the flexible-PPOS protocol, has emerged as a cost-effective and patient-friendly alternative. However, comparative data on embryo morphokinetics using time-lapse imaging and clinical outcomes between these protocols remain scarce. This study aimed to compare embryo morphokinetic parameters and clinical outcomes between flexible-PPOS and GnRH antagonist protocols in IVF-ICSI cycles.

This retrospective cohort study included 192 IVF-ICSI cycles and 892 embryos at Hanoi Obstetrics and Gynecology Hospital. Patients were divided into two groups based on the ovarian stimulation protocol: the Flexible-PPOS group (96 cycles, 403 embryos) and the GnRH-Antagonist group (96 cycles, 493 embryos). Embryos were cultured in a time-lapse imaging incubation system (TLI). Patient characteristics, clinical outcomes, laboratory results, and embryo morphokinetics were compared between groups. Statistical comparisons between groups were performed using appropriate parametric and non-parametric tests.

Patients\' characteristics were comparable between the flexible-PPOS and GnRH-antagonist groups, including mean age (31.31 ± 5.35 vs 32.03 ± 4.66 years, p = 0.321) and AMH levels (4.54 ± 2.99 vs 4.11 ± 2.81 ng/mL, p = 0.306). The flexible-PPOS group demonstrated shorter ovarian stimulation duration (9.75 ± 0.60 vs 10.05 ± 0.66 days, p = 0.0012) and significantly higher LH levels on trigger day (2.97 ± 3.37 vs 1.82 ± 1.69 IU/L, p = 0.00125), while total FSH dose and number of retrieved oocytes remained similar between groups. Clinical outcomes showed no statistically significant differences in implantation rates (55.2% vs 43.8%, p = 0.1123), clinical pregnancy rates (51.0% vs 37.5%, p = 0.0589) and live birth rates (38.54% vs 31.65%, p = 0.427). Similar embryo morphokinetics (tPNa, tPNf, t2, t3, t4, t5, t8, tB and KIDScore D5) were observed between the groups.

When compared to the GnRH-antagonist protocol, the flexible-PPOS protocol has similar clinical outcomes and embryo morphokinetics, with lower treatment costs and more patient – friendly.