P-222 Early blastulation on day 4 predicts ongoing pregnancy in fresh transfer cycles

Abstract Study question Do embryos with early blastulation (EB) on D4 show higher implantation potential compared to top D5 blastocysts in fresh elective single embryo transfer (eSET) cycles? Summary answer Fresh EB time start (tSB)<96.6h and of expanded blastocyst (tEB)<100h post-insemination is predictive ongoing pregnancy for patients <35. What known already Expansion hatching are correlated transfers. Thanks time-lapse morphokinetics, several time-points can be analyzed during embryonic growth. Embryos faster growing speed euploid status. The tSB < 96.6h, day 4 post-insemination, reported have significant value embryos, which found associated not only expansion scores, but also shorter tSB, full expansion, hatching. A study that significantly more reached the by 100h implanted those did not. design, size, duration Prospective observational a private hospital 2022. In 160 cycles (n = 81 cIVF n 79 ICSI) an was observed. 48 28 ICSI 20 cIVF) underwent eSET showing 4. Participants/materials, setting, methods Patients (tSB<96.6h, tEB<100h post-insemination) were enrolled regardless indication, female age, attempt’s rank or technique. Those included this study. Gardner’s classification used rate Embryoscope + (Vitrolife). outcome data (B3/B4 AA-AB-BA) (B4/B5 AA) reference group (female age ≤35). statistical analyses performed SPSS software. Main results role chance group, all transferred graded according as B3AA, B3AB, B3BA, B4AA, B4AB, B4BA. we chose ultra-top grade classified B4AA B5AA. obtained overall population 48) 92): 34.0 ± 3.8 vs 31.8 2.3, oocyte maturity (OM) 79.8% 80.3%, fertilization (FR) 80.0% 77.0%, (OBR) 78.1% 74.3%, (TBR) 59.1% 54.4%, total (PR) 75.5% 61.4%, (IR) 58.3 51.2% (OPR) 58.6% 47.1%, showed difference PR (p<0.05). younger 32.1 3.2 34) group: OM 75.1% FR 85.0% OBR 74.3%; TBR 58.7% 54.4% comparable between groups. observed (88.0% p<0.01) IR (70.6% vs. 51.2%, p<0.05) OPR p<0.05). Limitations, reasons caution small size sample needs order confirm encouraging findings larger population, especially older yielding aneuploid embryos. will continue 2023 compel live birth rate. Wider implications When available, best option D4. increased seems correlate euploidy advanced endometrial receptivity stimulated cycles. Higher even lower aneuploidy. Trial registration number applicable