Comparison of aneuploidy, pregnancy and live birth rates between day 5 and day 6 blastocysts

Abstract

Comprehensive chromosome screening is typically used for aneuploidy analysis of blastocysts. It is believed that either day of blastocyst development is acceptable. Euploidy rates and outcomes were examined between day 5 and day 6 blastocysts in two studies. First, euploidy rates of day 5 and day 6 blastocysts were examined on a per-embryo and per-patient basis. Second, outcomes were compared when only euploid day 5 or day 6 blastocysts were transferred in a cryopreserved embryo transfer cycle. In cycles (n = 70) that had blastocysts biopsied on both day 5 and day 6, day 5 blastocysts had a higher chance of being euploid than day 6 blastocysts (125/229 [54.6%]) and (77/180 [42.8%]), respectively (P = 0.0231). Similarly, euploid rates in blastocysts from patients (n = 193) with day 5 biopsy, day 6 biopsy, or both, were significantly higher in day 5 (235/421 [55.8%]) compared with day 6 (184/413 [44.6%]) blastocysts (P = 0.0014). In the second study, 50 women (36.1 ± 4.3 years) and 39 women (35.1 ± 3.8 years) with only euploid day 5 or euploid day 6 blastocysts transferred during a cryopreserved embryo transfer had similar cycle outcomes. Although underpowered, these data suggest that euploid day 6 blastocysts are as capable of positive outcomes as their euploid day 5 counterparts.

Pregnancy outcomes after day 5 versus day 6 blastocyst‐stage embryo transfer: A systematic review and meta‐analysis

“…The final inclusion was 13 studies that met the selection criteria for our meta‐analysis. Hence, 23 studies were included in the following meta‐analyses . The main characteristics and assessment for risk of bias of the included studies are presented in Table .…”

“…Although all studies have reported the pregnancy outcomes following transfer of frozen‐thawed blastocysts that had developed to blastocyst stage on day 5 or day 6, studies included in present meta‐analysis varied in terms of the number of embryo transferred and the chromosomal status of blastocysts. Only three studies transfer euploid blastocysts . Five studies only transfer one embryo per cycle, while remaining studies transfer no more than two blastocysts or more than two blastocysts per cycle .…”

“…Hence, 23 studies were included in the following meta-analyses. 4,6,7,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] The main characteristics and assessment for risk of bias of the included studies are presented in Table 1.…”

“…Only three studies transfer euploid blastocysts. 13,16,22 Five studies only transfer one embryo per cycle, [12][13][14]16,23 while remaining studies transfer no more than two blastocysts 11,[18][19][20]22,24,27,28 or more than two blastocysts per cycle. 29,30 The decision of when blastocyst was transferred in all included studies was dependent on the day of expansion.…”

D6 blastocyst transfer on day 6 in frozen-thawed cycles should be avoided: a retrospective cohort study

“…Zhan et al reported a significant higher euploid rates in D5 blastocysts than in D6 blastocysts (51.6% vs. 34.0%) [27]. Taylor et al also found that euploid rates were significantly higher in D5 blastocysts than in D6 blastocysts (55.8% vs. 44.6%,P = 0.0014), and when only euploid D5 or D6 blastocysts were transferred during FET cycles, there were no significant differences between them regarding the CPR, IR, or ongoing/live birth rates [28]. Similarly, Capalbo et al found that the ongoing pregnancy rate of euploid D5 and D6 blastocysts was similar(48.8% and 51.2%, respectively) [29].…”