Impact of embryo transfer at different development rates on clinical outcomes of assisted reproduction
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摘要:
目的 探讨不同发育速度的胚胎移植对辅助生殖临床结局的影响。 方法 对2015年1月1日至2023年12月31日在海军军医大学第一附属医院生殖医学中心接受体外受精和卵胞质内单精子注射胚胎移植助孕治疗的女性患者的临床数据进行回顾性分析。共有1 556个周期被纳入移植。第3天移植为A组，按胚胎发育至第3天的速度分为A1亚组(≤6个细胞阶段)、A2亚组(7~9个细胞卵裂胚阶段)、A3亚组(≥10个细胞卵裂胚阶段); 第4天移植为B组，按胚胎发育至第4天的速度分为B1亚组(卵裂胚阶段)、B2亚组(1期、2期囊胚或融合阶段)、B3亚组(3期及以上囊胚阶段); 第5天移植为C组，按胚胎发育至第5天的速度分为C1亚组(1期、2期囊胚或融合阶段)、C2亚组(4期或5期囊胚阶段)、C3亚组(6期囊胚阶段); 第6天移植为D组，按胚胎发育至第6天的速度分为D1亚组(1期、2期囊胚或融合阶段)、D2亚组(5期或6期囊胚阶段)。统计各组的临床妊娠率和活产率。 结果 胚胎发育速度均较慢的A1、B1、C1、D1亚组临床妊娠率分别为23.7%、37.3%、26.9%、35.9%(P＜0.05)，活产率分别为16.4%、28.4%、19.2%、26.9%(P＜0.05)，B1亚组临床妊娠率和活产率均最高; 胚胎发育速度均正常的A2、B2、C2、D2亚组临床妊娠率分别为58.0%、59.4%、62.2%、61.5%(P＜0.05)，活产率分别为47.5%、49.4%、53.8%、52.3%(P＜0.05)，C2亚组临床妊娠率和活产率均最高; 胚胎发育速度均较快的A3、B3、C3亚组临床妊娠率分别为62.2%、64.6%、63.5%(P＜0.05)，活产率分别为52.2%、56.9%、54.1%(P＜0.05)，B3亚组临床妊娠率和活产率均最高。 结论 在第4天移植发育速度快的囊胚可能获得更好的发育潜能和临床结局。发育速度较慢的胚胎建议培养到第4天移植，发育速度正常的胚胎建议培养到第5天移植。 Abstract:Objective To investigate the influence of different embryo development rates on the clinical outcomes of assisted reproductive technology (ART). Methods The clinical data of female patients who underwent in vitro fertilization and intracytoplasmic sperm injection embryo transfer in Reproductive Medicine Center of The First Affiliated Hospital of Naval Medical University from Jan. 1, 2015 to Dec. 31, 2023 were retrospectively analyzed. A total of 1 556 cycles were included. Group A was transferred on day 3, and they were assigned to subgroups according to the embryo development rates until day 3: subgroup A1 (≤6 cell stages), subgroup A2 (7-9 cell cleavage stages), or subgroup A3 (≥10 cell cleavage stages). Group B was transferred on day 4, and they were assigned to subgroups according to the embryo development rates until day 4: subgroup B1 (cleavage stages), subgroup B2 (1st or 2nd period blastocyst or morula stages), or subgroup B3 (3rd period blastocyst or higher stages). Group C was transferred on day 5, and they were assigned to subgroups according to the embryo development rates until day 5: subgroup C1 (1st or 2nd period blastocyst or morula stages), subgroup C2 (4th or 5th period blastocyst stages), or subgroup C3 (6th period blastocyst stages). Group D was transferred on day 6, and they were assigned to subgroups according to the embryo development rates until day 6: subgroup D1 (morula or 1st or 2nd period blastocyst stages), or subgroup D2 (5th or 6th period blastocyst stages). The clinical pregnancy and live birth rates were calculated for each group. Results Pairwise comparisons of the subgroups A1, B1, C1 and D1, all with relatively slow development rates, showed that the clinical pregnancy rates were 23.7%, 37.3%, 26.9% and 35.9%, respectively (P < 0.05), the live birth rates were 16.4%, 28.4%, 19.2% and 26.9%, respectively (P < 0.05), and the clinical pregnancy rate and live birth rate were both the highest in the B1 group. Pairwise comparisons of the subgroups A2, B2, C2 and D2 with normal development rates, the clinical pregnancy rates were 58.0%, 59.4%, 62.2% and 61.5%, respectively (P < 0.05), the live birth rates were 47.5%, 49.4%, 53.8% and 52.3%, respectively (P < 0.05), and the clinical pregnancy rate and live birth rate were both the highest in the subgroup C2. Pairwise comparisons of the subgroups A3, B3 and C3 with relatively fast development rates showed that the clinical pregnancy rates were 62.2%, 64.6% and 63.5%, respectively (P < 0.05), the live birth rates were 52.2%, 56.9% and 54.1%, respectively (P < 0.05), and the clinical pregnancy rate and live birth rate were both the highest in the subgroup B3. Conclusion The 4th day fast-developing blastocysts have better development potential and clinical outcomes. Embryos with slower development rate should be transferred on the 4th day, and embryos with normal development rate are recommended to be cultured and transferred to the 5th day. -
胚胎的质量评价是辅助生殖技术中一个非常重要的环节，直接关系到胚胎移植的成功率和临床妊娠结果，其中胚胎发育速度是移植时机和妊娠结局的重要影响因素之一。Li等[1]研究发现，培养第3天的胚胎细胞计数与囊胚发育阶段存在显著关联，培养第3天具有较高细胞计数(≥10个细胞)的胚胎更有可能在第5天达到更高级别的囊胚阶段，而第3天细胞计数较低(≤6个细胞)的胚胎更有可能在第6天形成囊胚。纪冰等[2]研究表明，发育速度较快的11~16个细胞胚胎可形成高质量囊胚，移植后可获得较好的临床结局。因此，胚胎在早期发育阶段的速度和质量可能对其最终的妊娠结果产生影响。一般认为发育速度快的胚胎其发育潜力较高，但也有研究发现此类胚胎具有较低的临床妊娠率[3-4]。本研究对不同移植时间中不同发育速度胚胎的临床结局进行分析，为临床医生在面对不同发育速度胚胎时的选择提供依据。
1 资料和方法
1.1 研究对象及分组
对2015年1月1日至2023年12月31日在在海军军医大学第一附属医院生殖医学中心接受体外受精(in vitro fertilization embryo transfer，IVF-ET)和卵胞质内单精子注射胚胎移植(intracytoplasmic sperm injection embryo transfer，ICSI-ET)助孕治疗的女性患者的临床数据进行回顾性分析。纳入标准：(1)患者年龄为25~35岁; (2)新鲜胚胎移植个数为1~2个; (3)采用促排卵长方案治疗; (4)若患者有多个移植治疗周期，选择第1个有移植的周期。排除标准：(1)存在染色体异常; (2)卵巢功能下降; (3)有子宫内膜异位症及输卵管病变; (4)生殖系统畸形; (5)瘢痕子宫，或子宫内膜容受性不良; (6)配偶存在严重少弱精症。根据以上纳排标准，共有1 556个周期纳入分析。分组如下：第3天移植为A组，按胚胎发育至第3天的速度分为A1亚组(≤6个细胞阶段)、A2亚组(7~9个细胞卵裂胚阶段)、A3亚组(≥10个细胞卵裂胚阶段); 第4天移植为B组，按胚胎发育至第4天的速度分为B1亚组(卵裂胚阶段)、B2亚组(1期、2期囊胚或融合阶段)、B3亚组(3期及以上囊胚阶段); 第5天移植为C组，按胚胎发育至第5天的速度分为C1亚组(1期、2期囊胚或融合阶段)、C2亚组(4期或5期囊胚阶段)、C3亚组(6期囊胚阶段); 第6天移植为D组，按胚胎发育至第6天的速度分为D1亚组(1期或2期囊胚或融合阶段)、D2亚组(5期或6期囊胚阶段)。本研究方案通过海军军医大学第一附属医院伦理委员会审批(CHEC 2019-12)。
1.2 控制性促排卵长方案
所有女性患者均使用卵泡期长方案进行控制性促排卵，于月经周期的第2~4天开始，皮下注射醋酸亮丙瑞林微球(商品名贝依，上海丽珠制药有限公司)3.75 mg; 在注射醋酸亮丙瑞林微球后的第28天达到降调标准后，加用重组人促卵泡激素(商品名果纳芬，德国默克公司)225 U皮下注射，连续注射7~10 d，根据卵泡发育大小调整重组人促卵泡激素剂量; 当卵泡直径≥18 mm时，注射重组人绒促性素注射液(商品名艾泽，德国默克公司)250 μg，36 h后取卵。获取的卵子体外孵育约5 h后进行体外操作。
1.3 囊胚评价
采用Gardner和Schoolcraft分级系统对囊胚、内细胞团和滋养层细胞进行评价[5]。囊胚分期：1期，即早期囊胚，囊胚腔体积小于囊胚整体体积的1/2;2期，囊胚腔体积大于囊胚整体体积的1/2;3期，完全囊胚，囊胚腔基本扩张至整个胚胎; 4期，囊胚扩张，胚胎体积继续扩大，囊胚腔亦继续扩张，透明带较前变薄; 5期，囊胚孵化，部分滋养层细胞从透明带破口扩张出; 6期，囊胚孵出，囊胚完全从透明带上逸出。对3期及以上阶段的囊胚进行内细胞团和滋养层分级。内细胞团分级：A级，细胞数量较多、排列整齐且紧密成团; B级，细胞数量变少、胞体连接松散; C级，只有零星的细胞; D级，未见细胞。滋养层分级：A级，细胞数量较多，形成连续紧密连接的上皮样结构; B级，细胞数量变少，细胞之间连接不紧密且不连续; C级，仅有零星的细胞; D级，未见细胞。
1.4 卵裂胚分级
胚胎卵裂期评定参照伊斯坦布尔共识[6]分级分为Ⅰ~Ⅳ级。Ⅰ级：卵裂球大小一致、完整且整齐，胞质干净均匀，碎片率≤10%;Ⅱ级：卵裂球大小略有不均，胞质呈粒状，碎片率为11%~20%;Ⅲ级：卵裂球大小明显不一致，形态明显不规则，胞质粗糙，颗粒现象明显，碎片率为21%~50%;Ⅳ级：卵裂球大小严重不一致，胞质粗糙、有严重的颗粒现象，碎片率在50%以上。评级Ⅰ级或Ⅱ级、卵裂球细胞数≥7个的胚胎定义为优质胚胎，可以移植、冷冻或进行囊胚培养。
1.5 移植胚胎和黄体支持
在自然周期或人工周期下监测子宫内膜厚度，在排卵当日或黄体生成素(luteinizing hormone，LH)达峰36 h左右，且子宫内膜厚度达8~15 mm时加用黄体酮凝胶(商品名雪诺同，英国Fleet laboratories Limited公司)90 mg/d。胚胎移植在腹部超声引导下进行，移植后10~12 d，检测血清人绒毛膜促性腺激素(human chorionic gonadotrophin，hCG)。如hCG阳性，黄体酮凝胶持续使用至孕10~12周。
1.6 资料收集及结局评估
收集各组的基础资料。所有患者在移植后2周内电话随访1次，在移植成功后的30 d左右行经阴道超声检查，见宫内孕囊伴原始心管搏动，则统计为临床妊娠。达预产期后30 d内电话随访1次，记录生产情况。临床妊娠率＝临床妊娠周期数/移植周期数×100%;活产率(%)＝活产周期数/移植周期数×100%。
1.7 统计学处理
采用SPSS 23.0软件进行统计学分析。计量资料以x±s表示，组间比较采用单因素方差分析或独立样本t检验; 计数资料以频次和百分数表示，组间比较采用χ2检验。检验水准(α)为0.05。
2 结果
2.1 各组一般资料比较
A、B、C、D各组间年龄、BMI、不孕年限、促性腺激素使用天数、促性腺激素使用剂量、血清基础雌二醇、血清基础卵泡刺激素、血清基础LH、hCG注射日子宫内膜厚度比较，差异均无统计学意义(均P＞0.05，表 1)。
表 1 各组接受辅助生殖助孕治疗的患者基础资料比较Table 1 Comparison of basic data of patients receiving assisted reproductive technology in each groupx±s Index Group A n＝587 Group B n＝312 Group C n＝449 Group D n＝208 Age/year 33.4±3.5 32.6±3.2 33.4±3.9 32.5±3.4 BMI/(kg•m－2) 24.8±3.8 24.7±3.2 23.5±4.1 23.8±3.9 Infertility duration/year 4.8±3.9 4.2±4.5 5.3±3.8 4.8±4.0 Gn day/d 9.9±1.8 10.2±2.2 9.7±1.9 9.8±1.7 Gn dose/U 2 367.0±672.8 2 377.3±698.2 2 298.8±796.7 2 246.5±612.7 Estradiol/(pmol•L－1) 40.6±14.5 40.3±13.3 41.3±15.8 42.4±14.5 Follicle-stimulating hormone/(U•L－1) 6.9±1.7 6.8±1.8 7.2±1.8 6.9±1.7 LH/(U•L－1) 4.5±1.5 3.8±1.6 3.9±1.3 4.1±1.5 Endometrial thickness on hCG day/mm 11.7±1.3 12.3±1.5 11.6±1.6 11.5±1.3 Group A to D: The objects received transplantation on the 3rd, 4th, 5th, and 6th day of embryonic development, respectively. BMI: Body mass index; Gn: Gonadotropin; LH: Luteinizing hormone; hCG: Human chorionic gonadotropin. 2.2 移植时间及胚胎发育速度对助孕结局的影响
由表 2可见，在第3天移植的患者中，A1、A2、A3亚组的临床妊娠率和活产率差异均有统计学意义(均P＜0.05)，其中发育速度较快的A3亚组临床妊娠率和活产率均最高; 在第4天移植的患者中，B1、B2、B3亚组的临床妊娠率和活产率差异均有统计学意义(均P＜0.05)，其中发育速度较快的B3亚组临床妊娠率和活产率均最高; 在第5天移植的患者中，C1、C2、C3亚组的临床妊娠率和活产率差异均有统计学意义(均P＜0.05)，其中发育速度较快的C3亚组临床妊娠率和活产率均最高; 在第6天移植的患者中，D1、D2亚组的临床妊娠率和活产率差异均有统计学意义(均P＜0.05)，其中发育速度正常的D2亚组临床妊娠率和活产率均较高。
表 2 不同胚胎移植时间和发育速度的各亚组患者的妊娠结局分析Table 2 Analysis of pregnancy outcomes of patients in different embryo groups with different development ratesn (%) Group Subgroup Cycle number, N Clinical pregnancy ratea Live birth ratea A A1 152 36 (23.7) 25 (16.4) A2 345 200 (58.0) 164 (47.5) A3 90 56 (62.2) 47 (52.2) B B1 67 25 (37.3) 19 (28.4) B2 180 107 (59.4) 89 (49.4) B3 65 42 (64.6) 37 (56.9) C C1 78 21 (26.9) 15 (19.2) C2 286 178 (62.2) 154 (53.8) C3 85 54 (63.5) 46 (54.1) D D1 78 28 (35.9) 21 (26.9) D2 130 80 (61.5) 68 (52.3) Group A to D: The objects received transplantation on the 3rd, 4th, 5th, and 6th day of embryonic development, respectively. Subgroups A1, B1, C1, and D1: The objects received transplantation with relatively slow development embryos; Subgroups A2, B2, C2, and D2: The objects received transplantation with normal development embryos; Subgroups A3, B3, and C3: The objects received transplantation with relatively fast development embryos. a: When comparing subgroups A1, A2, and A3, P＜0.05; comparing subgroups B1, B2, and B3, P＜0.05; comparing subgroups C1, C2, and C3, P＜0.05; comparing subgroups D1 and D2, P＜0.05; comparing subgroups A1, B1, C1, and D1, P＜0.05; comparing subgroups A2, B2, C2, and D2, P＜0.05; comparing subgroups A3, B3, and C3, P＜0.05. 由表 2可见，发育速度均较慢的A1、B1、C1、D1亚组临床妊娠率和活产率差异均有统计学意义(均P＜0.05)，其中第4天移植的B1亚组临床妊娠率和活产率均最高; 发育速度均正常的A2、B2、C2、D2亚组临床妊娠率和活产率差异均有统计学意义(均P＜0.05)，其中第5天移植的C2亚组临床妊娠率和活产率均最高; 发育速度均较快的A3、B3、C3亚组临床妊娠率和活产率差异均有统计学意义(均P＜0.05)，其中第4天移植的B3亚组临床妊娠率和活产率均最高。
3 讨论
在辅助生殖技术中，胚胎的发育速度是影响临床妊娠率的重要因素之一。本研究对既往接受IVF-ET和ICSI-ET助孕治疗的女性患者的的数据进行回顾性分析发现，在发育速度较慢的胚胎中，第4天移植发育速度较慢的胚胎比第3天移植发育速度较慢的胚胎有更高的临床妊娠率和活产率，提示对于发育速度较慢的胚胎，建议培养到第4天移植; 对于发育速度正常的胚胎，第5天移植比第6天移植有更高的临床妊娠率和活产率; 对于发育速度较快的胚胎，第4天移植有更好的发育潜能和临床结局。既往研究表明，发育到第3天的胚胎的细胞计数有助于预测囊胚发育程度，第3天具有较高细胞计数(≥10个细胞)的胚胎即发育速度较快的胚胎更有可能在第5天达到更高级别的囊胚阶段，但第3天细胞计数较低(≤6个细胞)的胚胎即发育速度慢的胚胎更有可能在第6天形成囊胚[1, 7-8]。还有研究表明随着第4天胚胎发育速度的增快，临床妊娠率和种植率逐渐增高[9]。这表明胚胎在早期发育阶段的速度和质量可能对其最终的妊娠结局产生影响。
囊胚形成的速度可能影响其后续的发育潜力和质量，快速形成囊胚表明胚胎可能具有较高的发育能力[10]。本研究结果显示，在第3天、第4天和第5天移植的胚胎中，相对于发育速度较慢的胚胎，发育速度较快的胚胎有更好的临床妊娠率和活产率，提示发育速度较快的胚胎有更好的发育潜能和临床结局。然而，也有研究报道，发育速度快的胚胎移植后流产率特别是晚期流产率显著升高，导致活产率降低[11]。这暗示了胚胎发育速度与流产率之间的潜在联系，其具体机制尚需进一步研究。
有研究表明，即使胚胎发育速度较慢，只要有足够的胚胎数量，囊胚阶段的移植仍然可以获得较好的妊娠结局[12]。另有研究发现，对于高质量级别囊胚，第5天和第6天移植的胚胎临床妊娠率和活产率无明显差异; 而对于低质量级别囊胚，第5天移植的临床妊娠率和活产率均高于第6天[13]。本研究通过回顾性分析发现，第4天移植发育速度较慢的胚胎比第3天、第5天移植发育速度较慢的胚胎有更高的临床妊娠率和活产率，提示对发育速度较慢的胚胎建议培养到第4天移植，也可获得较高的临床妊娠率和活产率。
根据既往文献报道，第5天形成的囊胚相较于第6天形成的囊胚有更高的临床妊娠率，表明胚胎发育速度较快的囊胚可能与较高的临床妊娠率相关联[14-15]。另有研究结果显示，第5天囊胚的整倍体率(euploidy rate)显著高于第6天囊胚(61.4% vs 38.1%，P＜0.001)，提示囊胚的发育速度与整倍体率相关，进而可能影响临床妊娠结局[16]。上述研究结果提示，改善胚胎的发育速度和质量可能有助于提高临床妊娠率。有研究发现，通过纺锤形视野辅助卵胞质内单精子注射联合辅助卵母细胞激活方法显著提高了以往低受精率患者的囊胚形成率，可能有助于获得更多可用于移植的胚胎[17]。此外，还有研究显示，通过人工智能胚胎评估软件实时记录胚胎发育过程中的分裂次数，可以更精确地评估胚胎的发育速度和质量，进而可能提高临床妊娠率[18]。对于发育速度较慢的胚胎是否也可以通过优化胚胎条件来激发其发育潜能，从而改善临床妊娠结局，是值得期待的一个研究方向。
综上所述，胚胎发育速度是影响辅助生殖技术临床妊娠率和活产率的重要因素，下一步研究我们拟探讨能否通过优化胚胎培养条件提高发育速度较慢胚胎的临床妊娠结局。未来需要进一步探索胚胎发育速度与妊娠结局之间关系的具体机制，以便更好地优化辅助生殖技术方案。
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表 1 各组接受辅助生殖助孕治疗的患者基础资料比较
Table 1 Comparison of basic data of patients receiving assisted reproductive technology in each group
x±s Index Group A n＝587 Group B n＝312 Group C n＝449 Group D n＝208 Age/year 33.4±3.5 32.6±3.2 33.4±3.9 32.5±3.4 BMI/(kg•m－2) 24.8±3.8 24.7±3.2 23.5±4.1 23.8±3.9 Infertility duration/year 4.8±3.9 4.2±4.5 5.3±3.8 4.8±4.0 Gn day/d 9.9±1.8 10.2±2.2 9.7±1.9 9.8±1.7 Gn dose/U 2 367.0±672.8 2 377.3±698.2 2 298.8±796.7 2 246.5±612.7 Estradiol/(pmol•L－1) 40.6±14.5 40.3±13.3 41.3±15.8 42.4±14.5 Follicle-stimulating hormone/(U•L－1) 6.9±1.7 6.8±1.8 7.2±1.8 6.9±1.7 LH/(U•L－1) 4.5±1.5 3.8±1.6 3.9±1.3 4.1±1.5 Endometrial thickness on hCG day/mm 11.7±1.3 12.3±1.5 11.6±1.6 11.5±1.3 Group A to D: The objects received transplantation on the 3rd, 4th, 5th, and 6th day of embryonic development, respectively. BMI: Body mass index; Gn: Gonadotropin; LH: Luteinizing hormone; hCG: Human chorionic gonadotropin. 表 2 不同胚胎移植时间和发育速度的各亚组患者的妊娠结局分析
Table 2 Analysis of pregnancy outcomes of patients in different embryo groups with different development rates
n (%) Group Subgroup Cycle number, N Clinical pregnancy ratea Live birth ratea A A1 152 36 (23.7) 25 (16.4) A2 345 200 (58.0) 164 (47.5) A3 90 56 (62.2) 47 (52.2) B B1 67 25 (37.3) 19 (28.4) B2 180 107 (59.4) 89 (49.4) B3 65 42 (64.6) 37 (56.9) C C1 78 21 (26.9) 15 (19.2) C2 286 178 (62.2) 154 (53.8) C3 85 54 (63.5) 46 (54.1) D D1 78 28 (35.9) 21 (26.9) D2 130 80 (61.5) 68 (52.3) Group A to D: The objects received transplantation on the 3rd, 4th, 5th, and 6th day of embryonic development, respectively. Subgroups A1, B1, C1, and D1: The objects received transplantation with relatively slow development embryos; Subgroups A2, B2, C2, and D2: The objects received transplantation with normal development embryos; Subgroups A3, B3, and C3: The objects received transplantation with relatively fast development embryos. a: When comparing subgroups A1, A2, and A3, P＜0.05; comparing subgroups B1, B2, and B3, P＜0.05; comparing subgroups C1, C2, and C3, P＜0.05; comparing subgroups D1 and D2, P＜0.05; comparing subgroups A1, B1, C1, and D1, P＜0.05; comparing subgroups A2, B2, C2, and D2, P＜0.05; comparing subgroups A3, B3, and C3, P＜0.05. -
[1] LI X, ZENG Y, ZHU L, et al. The association between pregnancy outcomes and frozen-thawed embryo transfer cycles based on D3 cell count in high-quality blastocysts[J]. Front Endocrinol (Lausanne), 2024, 15: 1464313. DOI: 10.3389/fendo.2024.1464313. [2] 纪冰, 马学工, 李晓娜, 等. 卵裂期胚胎发育速度对体外受精-胚胎移植临床结局的影响[J]. 检验医学与临床, 2024, 21(14): 2011-2015. DOI: 10.3969/j.issn.1672-9455.2024.14.006. [3] FISCH J D, SHER G, ADAMOWICZ M, et al. The graduated embryo score predicts the outcome of assisted reproductive technologies better than a single day 3 evaluation and achieves results associated with blastocyst transfer from day 3 embryo transfer[J]. Fertil Steril, 2003, 80(6): 1352-1358. DOI: 10.1016/j.fertnstert.2003.05.013. [4] DE CARVALHO B R, PAES BARBOSA M W, BONESI H, et al. Embryo stage of development is not decisive for reproductive outcomes in frozen-thawed embryo transfer cycles[J]. JBRA Assist Reprod, 2017, 21(1): 23-26. DOI: 10.5935/1518-0557.20170007. [5] GARDNER D K, SCHOOLCRAFT W B. Culture and transfer of human blastocysts[J]. Curr Opin Obstet Gynecol, 1999, 11(3): 307-311. DOI: 10.1097/00001703-199906000-00013. [6] Alpha Scientists in Reproductive Medicine and ESHRE Special Interest Group of Embryology. The Istanbul consensus workshop on embryo assessment: proceedings of an expert meeting[J]. Hum Reprod, 2011, 26(6): 1270-1283. DOI: 10.1093/humrep/der037. [7] EGGENHUIZEN G M, GO A, KOSTER M P H, et al. Confined placental mosaicism and the association with pregnancy outcome and fetal growth: a review of the literature[J]. Hum Reprod Update, 2021, 27(5): 885-903. DOI: 10.1093/humupd/dmab009. [8] XIAO Y, ZHANG P, WANG L, et al. Optimizing single blastocyst selection: the role of day 3 embryo morphology in vitrified-warmed blastocyst transfer cycles[J]. Reprod Biomed Online, 2024, 49(5): 104364. DOI: 10.1016/j.rbmo.2024.104364. [9] 陶林林, 郑波, 戴芳芳, 等. D4胚胎发育速度对体外受精-胚胎移植妊娠结局的影响[J]. 生殖医学杂志, 2023, 32(9): 1355-1362. DOI: 10.3969/j.issn.1004-3845.2023.09.009. [10] SUN L, WANG Y, YANG M, et al. Delayed blastocyst formation reduces the quality and hatching ability of porcine parthenogenetic blastocysts by increasing DNA damage, decreasing cell proliferation, and altering transcription factor expression patterns[J]. J Dev Biol, 2024, 12(4): 26. DOI: 10.3390/jdb12040026. [11] SHEN X, LI M, NIE Y, et al. The PPOS protocol mitigates the detrimental effects of high BMI on embryo and clinical pregnancy outcomes[J]. Reprod Biol Endocrinol, 2024, 22(1): 124. DOI: 10.1186/s12958-024-01294-8. [12] CORNELISSE S, FLEISCHER K, VAN DER WESTERLAKEN L, et al. Cumulative live birth rate of a blastocyst versus cleavage stage embryo transfer policy during in vitro fertilisation in women with a good prognosis: multicentre randomised controlled trial[J]. BMJ, 2024, 386: e080133. DOI: 10.1136/bmj-2024-080133. [13] HU J, ZHENG J, LI J, et al. D6 high-quality expanded blastocysts and D5 expanded blastocysts have similar pregnancy and perinatal outcomes following single frozen blastocyst transfer[J]. Front Endocrinol (Lausanne), 2023, 14: 1216910. DOI: 10.3389/fendo.2023.1216910. [14] NEGREIROS R A M, D'ASSUNÇÃO V R N, D'ASSUNÇÃO L E N, et al. Effect of day 5 or 6 blastocyst embryo transfer on pregnancy outcomes in euthyroid women undergoing IVF: a single centre retrospective cohort[J]. JBRA Assist Reprod, 2024, 28(4): 535-542. DOI: 10.5935/1518-0557.20240036. [15] GLUJOVSKY D, QUINTEIRO RETAMAR A M, ALVAREZ SEDO C R, et al. Cleavage-stage versus blastocyst-stage embryo transfer in assisted reproductive technology[J]. Cochrane Database Syst Rev, 2022, 5(5): CD002118. DOI: 10.1002/14651858.CD002118.pub6. [16] DONG K, WU C, HOU X, et al. Prediction of embryo euploidy and pregnancy outcome by blastocyst morphology and development speed for women receiving single embryo transfer[J]. J Obstet Gynaecol, 2024, 44(1): 2338235. DOI: 10.1080/01443615.2024.2338235. [17] LO W C, LIN C Y, LI C J, et al. The fertility outcome of assisted oocyte activation combined with spindle view-assisted intracytoplasmic sperm injection in patients with low fertilization rate[J]. Taiwan J Obstet Gynecol, 2024, 63(4): 513-517. DOI: 10.1016/j.tjog.2023.10.017. [18] 杨静薇, 韩伟, 刘卫卫, 等. 卵裂球计数曲线"跳变值"在胚胎AI评估中的应用[J]. 中华妇产科杂志, 2024, 59(7): 548-558. DOI: 10.3760/cma.j.cn112141-20240108-00023.
