Embryo stage of development is not decisive for reproductive outcomes in frozen-thawed embryo transfer cycles

Abstract

ObjectiveTo evaluate if the outcomes of IVF/ICSI in frozen-thawed embryo transfer and fresh embryo transfer cycles differ in relation to cleavage and blastocyst stages.MethodsRetrospective cohort study to compare IVF/ICSI outcomes between fresh embryo transfer and frozen-thawed embryo transfer cycles, according to the stage of embryo development. Analysis was carried out on 443 consecutive embryo transfer cycles performed between January 1st and December 31st, 2014. Women aged up to 38 and submitted to embryo transfer cycles with fresh (n = 309) or frozen-thawed (n = 134) embryos at a private center for assistance in human reproduction were considered for analysis. Results in each group were stratified according to the stage of embryo development: cleavage stage and blastocyst stage. Main outcome measures were implantation rate, clinical pregnancy rate, ongoing pregnancy rate and live birth rate per cycle.ResultsIn the fresh embryo transfer group, for cleavage stage versus blastocyst stage, respectively, implantation rates were 22% and 47% (p = 0.0005); clinical pregnancy rates were 34% and 64% (p = 0.0057); the ongoing pregnancy rates were 30% and 61% (p = 0.0046) and live birth rates were 28% and 55% (p = 0.0148). There were no significant differences in the rates between cleavage and blastocyst stages in the frozen-thawed group, neither between fresh and frozen-thawed cleavage embryo transfers nor between fresh and frozen-thawed blastocyst transfers.ConclusionOur results confirm that blastocyst transfer is better than cleavage stage in fresh embryo transfer cycles. In frozen-thawed cycles, cleavage or blastocyst stages seem to offer similar reproductive outcomes.

Comparison of pregnancy outcomes after vitrification at the cleavage and blastocyst stage: a meta-analysis

“…In addition, a study found that chromosome abnormalities were lower with BT compared to cleavage-stage embryo transfer [38]. BT prevents premature contact with an altered uterine environment after controlled ovarian stimulation, as supraphysiological concentrations of estrogen (E2) and progesterone (P) may influence endometrial receptivity [39,40]. However, it seems that the cumulative clinical pregnancy rate for cleavage-stage embryos is higher than that for blastocysts [41].…”

Frozen–thawed cleavage stage versus blastocyst stage embryo transfer in high responder patients

“…Conversely, Carvalho and colleagues stated that blastocyst transfer was preferable compared with cleavage stage transfer in fresh ET cycles. However, for frozen-thawed cycles, cleavage or blastocyst stage embryos seemed to offer comparable implantation rates for clinical and ongoing pregnancy and live birth (Carvalho et al, 2017). Surprisingly, Zue and colleagues found that blastocyst transfer in the first IVF cycle led to significantly higher pregnancy and live birth rates compared with cleavage ET, but this result was not significant for the second IVF cycle (Zhu et al, 2019).…”

Effect of extended embryo culture after thawing on clinical pregnancy rate

“…In FET cycles, both day 3 and day 5 transfer, had comparable implan-tation, pregnancy, and live birth rates. They concluded that in fresh cycles, the supraphysiologic estradiol levels resulting from controlled ovarian stimulation is negatively affecting the endometrium at day 3 but not at day 5 [9]. However, data from the Society for Assisted Reproductive Technology over ten years (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013) including almost 250,000 cycles indicated that for FET the odds of live birth increases 49% following blastocyst transfer as compared to cleavage stage embryos [10].…”