STUDY QUESTION

研究问题

Does the transfer of single low-grade blastocysts result in acceptable reproductive and perinatal outcomes compared to the transfer of single good-grade blastocysts?

与移植单个优质囊胚相比，移植单个低级别囊胚是否会获得可接受的生殖和围产期结局？

SUMMARY ANSWER

总结回答

The transfer of single low-grade blastocysts resulted in a reduced live birth rate of around 30% (14% for very low-grade blastocysts) compared to 44% for single good-grade blastocysts, but does not lead to more adverse perinatal outcomes.

与单个优质胚胎的移植相比（活产率44%），单个低质量胚胎的移植导致了约30%的活产率降低（非常低质量胚胎为14%），但不会导致更多不良围产期结果。

WHAT IS KNOWN ALREADY

已知情况

It is known that low-grade blastocysts can result in live births. However, the current studies are limited by relatively small sample sizes and single-centre designs. Furthermore, evidence on perinatal outcomes after transferring low-grade blastocysts is limited.

已知低级别的囊胚可以获得活产，然而，目前的研究受到相对较小的样本量和单中心设计的限制。此外，关于移植低级别囊胚后的围产儿结局的证据有限。

STUDY DESIGN, SIZE, DURATION

研究设计、规模、持续时间

We conducted a multi-centre, multi-national retrospective cohort study of 10 018 women undergoing 10 964 single blastocyst transfer cycles between 2009 and 2020 from 14 clinics across Australia, China, and New Zealand.

这是一项多地区、多中心回顾性队列研究，包括来自澳大利亚、中国和新西兰的14家诊所于2009年至2020年期间接受单囊胚移植的10018名妇女，共10964个周期。

PARTICIPANTS/MATERIALS, SETTING, METHODS

研究对象/材料、背景、方法

Blastocysts were graded individually based on assessment of the morphology and development of the inner cell mass (ICM) and trophectoderm (TE), and were grouped into three quality categories: good- (AB, AB, or BA), moderate- (BB), and low-grade (grade C for ICM or TE) blastocysts. CC blastocysts were individually grouped as very low-grade blastocysts. Logistic regression with generalized estimating equation was used to analyse the association between blastocyst quality and live birth as well as other reproductive outcomes. Binomial, multinomial logistic, or linear regression was used to investigate the association between blastocyst quality and perinatal outcomes. Odds ratio (OR), adjusted OR (aOR), adjusted regression coefficient, and their 95% CIs are presented. Statistical significance was set at P < 0.05.

根据内细胞团(ICM)和滋养外胚层(TE)的形态和发育情况，对囊胚进行单独分级，并将其分为三个质量等级：优质(AB、AB或BA)、中等(BB)和低级别(ICM或TE为C级)。CC囊胚被单独归类为极低级别囊胚。用Logistic回归和广义估计方程分析囊胚质量与活产及其他生殖结局之间的关系。采用二项式、多项式Logistic回归或线性回归分析囊胚质量与围产期结局之间的关系。给出了优势比(OR)、调整后的OR(aOR)、调整后的回归系数及其95%CI。两组比较，P<0.05差异有统计学意义。

MAIN RESULTS AND THE ROLE OF CHANCE

主要结果及偶然性作用

There were 4386 good-grade blastocysts, 3735 moderate-grade blastocysts, and 2843 low-grade blastocysts were included in the analysis, for which the live birth rates were 44.4%, 38.6%, and 30.2%, respectively. Compared to good-grade blastocysts, the live birth rate of low-grade blastocysts was significantly lower (aOR of 0.48 (0.41–0.55)). Very low-grade blastocysts were associated with an even lower live birth rate (aOR 0.30 (0.18–0.52)) and their absolute live birth rate was 13.7%. There were 4132 singleton live births included in the analysis of perinatal outcomes. Compared with good-grade blastocysts, low-grade blastocysts had comparable preterm birth rates (<37 weeks, aOR 1.00 (0.65–1.54)), birthweight Z-scores (adjusted regression coefficient 0.02 (0.09–0.14)), and rates of very low birth weight (<1500 g, aOR 0.84 (0.22–3.25)), low birth weight (1500–2500 g, aOR 0.96 (0.56–1.65)), high birth weight (>4500 g, aOR 0.93 (0.37–2.32)), small for gestational age (aOR 1.63 (0.91–2.93)), and large for gestational age (aOR 1.28 (0.97–1.70)).

纳入分析的囊胚数为：优质囊胚4386枚，中级囊胚3735枚，低级囊胚2843枚，活产率分别为44.4%，38.6%，30.2%。与优质囊胚相比，低级囊胚的活产率显著降低(aOR:0.48(0.41~0.55))。极低级别的囊胚与更低的活产率(aOR 0.30(0.18-0.52))相关，其活产率为13.7%。有4132例单胎活产纳入围产儿结局分析。与优质囊胚相比，低级囊胚的早产率(<37周，aOR 1.00(0.65~1.54))、出生体重Z评分相似。

LIMITATIONS, REASONS FOR CAUTION

局限性，谨慎的理由

Due to the nature of the retrospective design, residual confounding could not be excluded. In addition, the number of events for some perinatal outcomes was small. Between-operator and between-laboratory variations in blastocyst assessment were difficult to control.

由于回顾性设计的性质，不能排除混杂因素影响。此外，一些围产期结局的事件数量很少，囊胚评估中操作员之间和实验室之间的差异也很难控制。

WIDER IMPLICATIONS OF THE FINDINGS

研究结果更广泛的含义

Patients undergoing IVF should be informed that low-grade blastocysts result in a lower live birth rate, however they do not increase the risk of adverse perinatal outcomes. Further research should focus on the criteria for embryos that should not be transferred and on the follow-up of long-term outcomes of offspring.

接受体外受精治疗的患者应被告知，移植低级别的囊胚后活产率会下降，但不会增加不良围产期结局的风险。进一步的研究应该关注不宜移植的胚胎的标准，以及后代的长期结果的跟踪。

文章来源：

Haowen Zou, James M Kemper, Elizabeth R Hammond, Fengqin Xu, Gensheng Liu, Lintao Xue, Xiaohong Bai, Hongqing Liao, Songguo Xue, Shuqin Zhao, Lan Xia, Jean Scott, Vincent Chapple, Masoud Afnan, Dean E Morbeck, Ben W J Mol, Yanhe Liu, Rui Wang, Blastocyst quality and reproductive and perinatal outcomes: a multinational multicentre observational study, Human Reproduction, Volume 38, Issue 12, December 2023, Pages 2391–2399, https://doi.org/10.1093/humrep/dead212