O-144 Critical assessment of possible clinical benefits of culturing human embryos until day 7

Abstract Study question Is there any benefit of extending culture until day (D) 7 to increase euploid blastocysts yield and clinical outcomes in a PGT-Aneuploidy analysis (PGT-A) program? Summary answer Extended D7 increases cumulative live birth. Highest was observed patients aged ≤41 with ≤2 D5/D6 biopsied. What is known already It well-known that female age the strongest predictive factor embryo aneuploidy has been associated delayed blastocyst development vitro. Culturing embryos might biopsied yields euploidy among women undergoing ART as published. However, extended IVF workload implies extra cost. unclear whether practice justified when certain number have on D5/D6. Therefore, additive value needs further evaluation. Studies published literature small sample sizes are controversial. design, size, duration This single center observational study included 30,941 from 6,976 consecutive IVF/ICSI PGT-A fresh autologous cycles performed between 2017 2022. Patients who underwent by Next Generation Sequencing (NGS) were considered for analysis. Only graded ≥BL3CC (Gardner) TE biopsy D5, D6 or included. Data stratified categories (<37, 37-41 >41) D5 and/or culture. Participants/materials, setting, methods The assessed terms absolute numbers (percentage obtained) theoretical birth rate (having at least 1 using all available blastocysts) calculated binomial density function. Results strata 37-41, (No biopsy, ≤2, 3-4, 5-6 ≥ 6 biopsied). Main results role chance A total 18,478 (38.5%), (55.2%) D7(6.3%). Euploidy decreased significantly (55.6%, 39.7% 27.1%, P < 0.001, respectively). When stratifying age, rates consistently higher compared (<37: 61.1%, 50.0% 38.5%, 0.001; 37-41: 39.0%, 27.8% 20.1%, >41: 18.5%, 9.0% 3.9%, D7, chances obtaining one <37 37–41 years > 41 (7.2% 4.4% vs. 0.6%, 0.001). Among <37, 25% (theoretical) detected 10.1% no D5/D6, 2.5% 1-2 only 0.3% ≥3 (P In older (37-41), found 5.6% 0.4% Women >41 rarely benefited util (<1%) regardless Limitations, reasons caution based retrospective data While this provides largest analyzed “freeze all” strategy, should not be extrapolated other populations different routine practices. Wider implications findings Usable (6.3%) (27.1%) lower blastocysts. do (<1%). days mainly decided D6. Trial registration applicable