Time to blastulation is superior to individual components of embryo grading for live-birth prediction

Abstract

Objective: To compare components of the embryo grading system with time for blastocyst formation (i.e., day of embryo transfer) for predicting live-birth rate in frozen embryo transfer cycles. Design: Retrospective cohort study. Setting: University-affiliated fertility clinic. Patient(s): From January 2015 to October 2018, 870 frozen embryos transferred in a total of 509 women and 728 cycles at our institution. Intervention(s): None. Main Outcome Measure(s): Probability of live birth per cycle. Result(s): In unadjusted analysis of embryo grading components, both inner cell mass (ICM) and trophectoderm grades demonstrated a correlation with live-birth rates. However, this effect was lost in the ICM subgroup analysis by day of embryo transfer and preserved only in declining trophectoderm grades of day-6 transfers. In the adjusted analysis for prediction of live birth, only day of transfer was statistically significant. When assessing the composite score by Society for Assisted Reproductive Technology (SART) embryo grading, good embryos that blastulated on day 6 were statistically significantly less likely than day-5 embryos to result in live birth (risk ratio 0.70; 95% confidence interval, 0.58-0.85). Finally, in a predictive model adjusted for all individual components of embryo grade, the day of blastulation was the only statistically significant contributor. Conclusion(s): Time to blastulation is superior to other individual components of embryonic grading for prediction of live birth. (Fertil Steril Rep Ò 2020;1:243-8. Ó2020 by American Society for Reproductive Medicine.

Blastulation time measured with time-lapse system can predict in vitro viability of bovine blastocysts

“…However, the determination of the impact of the blastulation moment is little studied [ 65 , 66 ]. In humans, Ho et al [ 14 ] and Moustafa et al [ 16 ] indicated that time of blastulation has a high potential for embryo selection over other embryo morphologic grading components. Likewise, Lee et al [ 15 ].…”

“…Likewise, Lee et al [ 15 ]. and Moustafa et al, [ 16 ]. reported that embryos with chromosomal abnormalities (aneuploid and mosaic) showed delayed blastulation.…”

“…Early embryonic development involves a series of orchestrated events between the first cell cleavages and the differentiation of the first cell lineages [11,12], leading to the differentiation of the inner cell mass into hypoblast and epiblast (blastocyst formation) important events for the implantation of the embryo in the uterus [13]. Also, in humans, blastulation timing is associated with mitochondrial content, chromosome status, and embryonic quality and competence [14][15][16], synchrony between embryo development and endometrial receptivity [17] and high precision of pregnancy rate (80%; [18]). In cattle, blastulation timing may have a high potential for embryo selection over other embryo morphologic parameters and may be a criterion for the selection of blastocysts to be transferred that can predict the embryo viability or competence.…”

Euploid day 7 blastocysts of infertility patients with only slow embryo development have reduced implantation potential

“…One group reported that the implantation rate after euploid single FET was not different for D5 versus D6 embryos, and was unaffected by embryo grade (Viñals Gonzalez et al 2019). Another study compared FET outcomes of D5 and D6 unscreened embryos and reported that day of blastulation was a significant predictor of live birth, whereas embryo morphological grade was not (Moustafa et al 2020). Coello et al recently identified higher live birth rates following transfer of unscreened D5 embryos compared to D6, and with trophectoderm grade A compared to C (2021).…”