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Meta-Analysis
. 2020 Apr;46(4):595-605.
doi: 10.1111/jog.14188. Epub 2020 Feb 5.

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

Yi-Xin Li  1   2   3 , Jin Wang  4 , Tian-Ze Sun  2   3   5 , Mo-Qi Lv  1   2   3 , Pan Ge  1   2   3 , Hao-Nan Li  2   3   6 , Dang-Xia Zhou  1   2   3
Affiliations
Meta-Analysis

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

Yi-Xin Li et al. J Obstet Gynaecol Res. 2020 Apr.

Abstract

Aim: To compare the pregnancy outcomes after day 5 blastocyst-stage embryo transfers (BET) versus day 6 BET following vitrified-warmed cycle and to evaluate whether the number of embryos transferred and the chromosomal status of embryo influence effect estimates.

Methods: A literature search (PubMed, Embase and MEDLINE) up to January 2019 was conducted to identify studies where women with day 6 BET were compared to women with day 5 BET. Only studies published in English language, on peer-reviewed journal were considered eligible. The following subgroup analyses were performed: (i) number of embryos transferred and (ii) chromosomal status of embryo.

Results: From a total of 1956 articles identified, 23 observational studies were included in the meta-analysis. We observed that day 6 BET were associated with lower implantation rate (risk ratio, RR: 1.17, 95% confidence interval, CI: 1.10-1.24), clinical pregnancy rate (RR: 1.17, 95% CI: 1.10-1.24), ongoing pregnancy rate (RR: 1.15, 95% CI: 1.07-1.24) and live birth rate (RR: 1.22, 95% CI: 1.11-1.33) than day 5 BET following vitrified-warmed cycle. The subgroup analysis found that the superiority of day 5 BET compared with day 6 BET is influenced by the number of embryos transferred and chromosomal status of embryos.

Conclusion: Current evidence shows that day 5 BET is superior to day 6 BET following vitrified-warmed cycle in clinical practice. Due to the overall low quality of available evidence, more larger and well-conducted studies are needed to compare the pregnancy outcomes between day 5 and day 6 BET before drawing a clear conclusion.

Keywords: assisted reproduction; blastocysts; day 5; day 6; pregnancy outcomes; vitrification.

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References

    1. Glujovsky D, Farquhar C, Quinteiro Retamar AM, Alvarez Sedo CR, Blake D. Cleavage stage versus blastocyst stage embryo transfer in assisted reproductive technology. Cochrane Database Syst Rev, (6) 2016: Cd002118.
    1. Poulsen V, Ingerslev HJ, Kirkegaard K. Elective embryo transfers on day 6 reduce implantation compared with transfers on day 5. Hum Reprod 2017; 32: 1238-1243.
    1. Fragouli E, Alfarawati S, Spath K, Wells D. Morphological and cytogenetic assessment of cleavage and blastocyst stage embryos. Mol Hum Reprod 2014; 20: 117-126.
    1. Kovalevsky G, Carney SM, Morrison LS, Boylan CF, Neithardt AB, Feinberg RF. Should embryos developing to blastocysts on day 7 be cryopreserved and transferred: An analysis of pregnancy and implantation rates. Fertil Steril 2013; 100: 1008-1012.
    1. Shapiro BS, Daneshmand ST, Garner FC, Aguirre M, Ross R. Contrasting patterns in in vitro fertilization pregnancy rates among fresh autologous, fresh oocyte donor, and cryopreserved cycles with the use of day 5 or day 6 blastocysts may reflect differences in embryo-endometrium synchrony. Fertil Steril 2008; 89: 20-26.

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