Over Ten-Cell Good Embryo Transfers on Day Three have Equivalent Clinical Outcomes with Those of Eight-Cell Embryos in Female Patients Aged ≤35 Years: A Retrospective Cohort Study

Abstract

Background/Aim: To compare the clinical outcomes between > 10- and 8-cell good quality embryos on day 3. Methods: A retrospective study of a cohort of 459 patients was included in the fresh embryo transfer (ET) cycle group from January 2009 to April 2016. In this group, 2 good quality embryos on day 3, were transferred on corresponding dates, in 75 patients (> 10-cell embryos), and in 384 patients (8-cell embryos). Seven hundred and forty four patients, with 1 blastocyst transferred derived from > 10-cell (n = 183) or 8-cell (n = 561) good quality embryos on day 3, were assigned in the frozen ET (FET) group. Results: In the ET group, the clinical pregnancy and live birth rates of the > 10-cell transfer patients were comparable with those of the 8-cell transfer group (62.67 vs. 69.27%, 60.00 vs. 59.90%, respectively); however, the miscarriage rate of > 10-cell transfers was significantly lower than that of 8-cell transfers (4.26 vs. 13.53%, p < 0.05). In the FET group, there were no statistically significant differences found in the clinical pregnancy, live birth, and miscarriage rates between one > 10-cell-derived and one 8-cell-derived blastocyst transfers (71.04 vs. 65.78%, 59.02 vs. 54.19%, and 16.92 vs. 17.62%, respectively). Conclusions: The results suggested that > 10- and 8-cell, good quality embryos on day 3, had comparable viability and clinical outcomes.

Increased blastomere number is associated with higher live birth rate in day 3 embryo transfer

“…Nonetheless, these results were contradicted with Moayeri et al [24] showing that cellular fragmentation, instead of cell number, acted as a sensitive proxy for predicting chromosomally normal embryos. In another retrospective study, Zhao et al [15] also found that > 10-cell derived blastocysts had similar aneuploidy rates to 8-cell derived blastocysts (55.6% vs. 55.9%). More recently, Pons et al [13] analyzed the PGT-A data of 4028 embryos in total and further confirmed that the ploidy of > 11-cell embryos was comparable with that of 8-cell embryos at the blastocyst stage (OR 1.20, 95% CI 0.92-1.56).…”

“…To our knowledge, only limited studies have been conducted to investigate the impact of increased day 3 cell number on clinical outcomes of cleavage-stage embryo transfer cycles [6,14,15]. Based on the national SART CORS database, Racowsky et al [6] found that there was a significant decline in LBR from embryos comprised of 8 cells to those with higher cell counts.…”

“…This study was strengthened by the continuous monitoring with time-lapse imaging but similarly, no multivariate analyses were performed to confirm the results. To add further to the confusion, Zhao et al [15] reported comparable LBR (60.0% vs. 59.90%; P = 0.98) but reduced miscarriage rate (4.3% vs. 13.5%; P = 0.04) in patients transferred with > 10-cell embryos compared to the 8-cell transfer group. However, all cycles were double rather than single embryo transfers and merely 75 cycles were involved in the > 10-cell group.…”

“…To our knowledge, only limited studies have been conducted to investigate the impact of increased day 3 cell number on clinical outcomes of cleavage-stage embryo transfer cycles [ 6 , 14 , 15 ]. Based on the national SART CORS database, Racowsky et al .…”

“…To date, only little research has focused on the LBR following fast-cleaving day 3 embryo transfer, which could be the primary endpoint in IVF treatment [ 6 , 14 , 15 ]. Hampered by small sample size and inadequate confounder adjustment, these studies also came up with inconsistent conclusions.…”