AIM: Using oocyte donation cycles as an ideal model, we sought to compare pregnancy and implantation rates in cleavage stage (day 3) versus blastocyst stage (day 6) embryo transfers (ET); assess the predictive value of blastocyst formation rates based on cleavage cell stage and morphology grade; and evaluate the ability to predict formation of high quality (HQ) blastocysts. METHODS: Ninety three consecutive oocyte donation cycles from July 2003 to August 2005 were retrospectively evaluated and analyzed to determine if either resulted in a cleavage stage (n = 30) or blastocyst (n = 45) ET. The primary outcomes measured pregnancy rates, the percent development of HQ blastocysts based on day 3 embryo status, and the ability to select day 3 embryos suitable for transfer among four blinded evaluators by assessing their day 6 embryo outcome. RESULTS: Cleavage stage ET resulted in significantly lower pregnancy rates, clinical pregnancy rates, and implantation rates (47% [n = 14/30]; 40% [n = 12/30] and 27 + or - 7%) compared to blastocyst stage (82% [n = 37/45]; 73% [n = 33/45] and 64 + or - 6% [+ or -SE], P < 0.01). In total, HQ blastocysts resulted from high and good quality day 3 embryos 35% (191/546) and 17% (93/546), respectively. Blinded evaluation revealed at least one, two or all three day 3 embryos were correctly selected for ET on day 6, 97%, 67% and 19%, respectively. CONCLUSION: Day 6 ET resulted in significantly better clinical outcomes compared to day 3 ET. While day 3 status is not predictive of blastocyst quality, the selection of at least one day 3 embryo ultimately suitable for blastocyst ET underscores the significance of optimal endometrial receptivity.
AIM: Using oocyte donation cycles as an ideal model, we sought to compare pregnancy and implantation rates in cleavage stage (day 3) versus blastocyst stage (day 6) embryo transfers (ET); assess the predictive value of blastocyst formation rates based on cleavage cell stage and morphology grade; and evaluate the ability to predict formation of high quality (HQ) blastocysts. METHODS: Ninety three consecutive oocyte donation cycles from July 2003 to August 2005 were retrospectively evaluated and analyzed to determine if either resulted in a cleavage stage (n = 30) or blastocyst (n = 45) ET. The primary outcomes measured pregnancy rates, the percent development of HQ blastocysts based on day 3 embryo status, and the ability to select day 3 embryos suitable for transfer among four blinded evaluators by assessing their day 6 embryo outcome. RESULTS: Cleavage stage ET resulted in significantly lower pregnancy rates, clinical pregnancy rates, and implantation rates (47% [n = 14/30]; 40% [n = 12/30] and 27 + or - 7%) compared to blastocyst stage (82% [n = 37/45]; 73% [n = 33/45] and 64 + or - 6% [+ or -SE], P < 0.01). In total, HQ blastocysts resulted from high and good quality day 3 embryos 35% (191/546) and 17% (93/546), respectively. Blinded evaluation revealed at least one, two or all three day 3 embryos were correctly selected for ET on day 6, 97%, 67% and 19%, respectively. CONCLUSION: Day 6 ET resulted in significantly better clinical outcomes compared to day 3 ET. While day 3 status is not predictive of blastocyst quality, the selection of at least one day 3 embryo ultimately suitable for blastocyst ET underscores the significance of optimal endometrial receptivity.
Authors: Sarah M Capelouto; Audrey J Gaskins; Zsolt Peter Nagy; Daniel B Shapiro; Jessica B Spencer; Heather S Hipp Journal: J Assist Reprod Genet Date: 2021-04-05 Impact factor: 3.357