The Valuable Reference of Live Birth Rate in the Single Vitrified-Warmed BB/BC/CB Blastocyst Transfer: The Cleavage-Stage Embryo Quality and Embryo Development Speed
Xi Shen, Hui Long, Hongyuan Gao, Wenya Guo, Yating Xie, Di Chen, Yanyan Cong, Yun Wang, Dongying Li, Jiqiang Si, Leiwen Zhao, Qifeng Lyu, Yanping Kuang, Li Wang
Abstract
Background: It is unclear whether we should focus attention on cleavage-stage embryo quality and embryo development speed when transferring single particular grade vitrified-warmed blastocysts, especially in poor-quality blastocysts (grade ‘C’). Method: This retrospective study considered 3386 single vitrified-warmed blastocyst transfer cycles from January 2010 to December 2017. They were divided into group 1 (AA/AB/BA, n = 374), group 2 (BB, n = 1789), group 3 (BC, n = 901) and group 4 (CB, n = 322). The effects of cleavage-stage embryo quality and embryo development speed were measured in terms of clinical pregnancy and live birth rates in each group. Results: Pregnancy outcomes showed a worsening trend from groups 1 to 4; the proportion of embryos with better cleavage-stage quality and faster development speed decreased. In group 1, only the blastocyst expansion degree 3 was a negative factor in the clinical pregnancy rate (Odds ratio (OR) [95% confidence interval (CI)]: 0.233[0.091-0.595]) and live birth rate (0.280[0.093-0.884]). In the other groups (BB, BC and CB), blastocysts frozen on day 5 had significantly better clinical pregnancy outcomes than those frozen on day 6 :1.373 [1.095–1.722] for group 2, 1.523 [1.055–2.197] for group 3, and 3.627 [1.715–7.671] for group 4. The live birth rate was: 1.342 [1.060–1.700] for group 2, 1.544 [1.058–2.253] in group 3, 3.202 [1.509–6.795] in group 4, all P 7) for live birth rate in group 4 (2.455 [1.190–5.063], P7) and AA/AB/BA grade blastocysts with degrees of expansion (≥4) to obtain better pregnancy outcomes.