P-311 Embryo morphological grade and day of vitrification can impact the outcome of a single euploid frozen embryo transfer (FET)

Abstract Study question How does the embryo morphological grade and day of vitrification affect FET outcomes from in vitro fertilization cycles utilizing preimplantation genetic testing for aneuploidy (PGT-A)? Summary answer The a transferred affects age groups differently, Day-5 embryos have significantly better pregnancy than Day-6 embryos. What is known already use PGT-A has shown to increase implantation rates, lower miscarriage rates promote counseling single transfer. Although euploid are priority transfer, it important examine characteristics that may influence these within maximize outcome each FET. design, size, duration In this retrospective study, 1,554 FETs transferring one or between January 2020 October 2022 were evaluated, with exclusion donor oocyte, embryo, gestational carrier Day-7 transfer cycles. inner cell mass trophectoderm categorized as good (G), fair (F) poor (P) respectively at time cryopreservation. A total 282 GG, 1,053 FG, 209 FF transferred. Participants/materials, setting, methods Embryo categories used compare versus by groups. Separating < 34, 34-37, ≥38 eliminated significant factor. Primary included positive chemical (CP), biochemical loss (BL), clinical uterine gestation (CIG), fetal cardiac activity (FCA). Independent t-tests compared age, aggregate data was analyzed proportional z-tests. p-value <0.05 defined statistically 95% confidence interval. Main results role chance Age BL not days had higher CP (GG: 84% vs 65%, p 0.001; FG: 75% 59%, = 0.006; FF: 63% 44%, 0.019), CIG 73% 57%, 64% 48%, 55% 34%, 0.007), FCA 66% 52%, 0.022, 60% 40%, 0.001, 30%, 0.001). For patients <34, GG FG (74% 64%, 0.017; 74% 46%, 0.001), (66% 55%s, 0.011; 38%, 0.001) (61% 50%, 0.012; 61% (64% 0.007) (55% 0.008) FF. (78% 53, 70% 53%, 0.004), 42%, 0.002; 56% 0.029), (58% 35%, 50% 0.011) When ≥38, increased (79% 47%, 0.012) (65% 36%, 0.004; 53% 0.010). Only (56% 0.049). Limitations, reasons caution Even criteria, nature study be viewed limitation, so significance should evaluated further. Wider implications findings Based on results, demonstrates need before selection pregnancy. Embryos vitrified especially prioritized over Trial registration number applicable