Comparison of the pregnancy and obstetric outcomes between single cleavage-stage embryo transfer and single blastocyst transfer by time-lapse selection of embryos

Abstract

To compare the pregnancy and obstetric outcomes following single cleavage-stage embryo transfer (SCT) and single blastocyst transfer (SBT) using time-lapse imaging (TLI), a total of 2066 normally fertilized and cleaved embryos from 233 patients were divided into Day 3 SCT group (n = 171) and Day 5 SBT group (n = 62) according to patient’s willingness. Embryo selection criteria were based on embryo cleavage patterns, timing parameters, and blastocyst quality. The pregnancy and obstetric outcomes of each group were evaluated. There were no statistically significant differences with regard to pregnancy outcomes including the implantation rate, early abortion rate, ongoing pregnancy rate and live birth rate, and obstetric outcomes including preterm birth rate, gestational week, birth height, birth weight and fetal malformation rate between SCT group and SBT group. SBT group had significantly higher monozygotic twinning (MZT) rates than SCT group (6.98% vs. 0, p < .05). Although not statistically significant, there was a trend of higher proportion of male-to-female sex ratio at birth in SBT group than SCT group (1.38 vs. 1.05). Based on the combination of cleavage patterns and timing parameters, SCT may be an alternative to SBT because it can provide similar pregnancy and obstetric outcomes and meanwhile lower monozygotic twinning rates.

Chinese abstract

使用延时成像技术将来自233名患者共2066个正常受精和分裂的胚胎根据患者意愿分为第3天单卵裂期胚胎移植（SCT）组（n = 171）和第5天单囊胚移植（SBT）组（n = 62）, 比较两组的妊娠和产科结局。胚胎选择标准基于胚胎卵裂模式, 时间参数和囊胚质量。评估每组的妊娠和产科结局。两组妊娠结局无显著统计学差异, 包括植入率, 早期流产率, 持续妊娠率和活产率。两组产科结局, 包括早产率, 孕周, 出生身高, 出生体重和胎儿畸形率亦无统计学差异。 SBT组的单卵双胎（MZT）发生率明显高于SCT组（6.98％vs。0, p <.05）。SBT组出生时男女性别比高于SCT组（1.38 vs. 1.05）, 但无统计学意义。结合卵裂模式和时间参数, SCT与SBT妊娠和产科结局相似, 同时降低了单卵双胎发生率, 可替代SBT。

Keywords:

• Pregnancy outcomes
• obstetric outcomes
• time-lapse imaging
• single cleavage-stage embryo transfer
• single blastocyst transfer

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The study was funded by National Natural Science Foundation of China [No. 81601277], the Science and Technology Development Projects in Nanjing [YKK15074] and Merck Serono China Research Fund for Fertility Experts, CREATE.