生殖医学杂志

目的 探讨不同年龄女性D3卵裂期胚胎细胞数对囊胚发育潜能的影响，为临床优选胚胎提供参考。方法 回顾性分析行囊胚培养的29 314枚D3卵裂期胚胎情况，按照女方年龄分为<35岁组和≥35岁组，再按照卵裂期胚胎细胞数分为4细胞～11⁺细胞和融合期胚胎9个亚组，比较不同年龄组中不同细胞数亚组的囊胚形成率。行单囊胚冻融移植的共2 402个周期，其中<35岁组和≥35岁组中又根据囊胚来源的D3胚胎细胞数分为4～6细胞、7～9细胞和≥10细胞+融合期3个亚组，比较不同年龄不同细胞数胚胎来源的囊胚冻融移植临床结局。同时分析1 069个行胚胎植入前非整倍体检测(PGT-A)囊胚中<35岁组和≥35岁组4～6细胞、7～9细胞和≥10细胞+融合期3个亚组的整倍体率情况。结果 (1)<35岁组和≥35岁组中，8细胞亚组发育成囊胚的潜能最高，融合期胚胎次之，而6细胞以下亚组明显劣于其他细胞数目亚组(P<0.05)。(2)<35岁组中，各细胞数D3胚胎发育潜能层次明显，按照可利用囊胚形成率从高到低依次排序为：8细胞>融合期>11⁺细胞=9细胞>10细胞=7细胞>6细胞>5细胞=4细胞；≥35岁组中按上述排序为：8细胞=融合期>9细胞=7细胞=11⁺细胞=10细胞>6细胞=4细胞>5细胞。(3)<35岁组的临床妊娠率、活产率和整倍体率显著高于≥35岁组(P<0.001)。<35岁组中，4～6细胞亚组冻融单囊胚移植的临床妊娠率和活产率显著低于7～9细胞和≥10细胞+融合期亚组(P<0.05);≥35岁组中各细胞数亚组的临床妊娠率、活产率无显著性差异(P>0.05)。(4)<35岁组和≥35岁组中，各细胞数D3胚胎来源的囊胚整倍体率无显著性差异(P>0.05)。结论 不同年龄女性D3卵裂期胚胎细胞数与囊胚形成呈现不同的发育规律。<35岁组中，各细胞数卵裂期胚胎的囊胚发育潜能层次明显；4～6细胞D3胚胎来源的囊胚行冻融单囊胚移植的妊娠结局低于其他细胞数组。≥35岁组中，冻融单囊胚移植的妊娠结局不受囊胚来源的D3胚胎细胞数影响，只要有囊胚形成则能保持较满意的妊娠率。

Objective:To investigate the effect of cells number of Day 3 embryos at cleavage stage on blastocyst development potential, and to provide reference for clinical embryo selection.Methods:The status of 29 314 Day 3 embryos at cleavage stage were retrospectively analyzed. The embryos were divided into two groups according to the female age: <35 years old group and ≥35 years old group. Then, the embryos were divided into 9 subgroups: 4 cells to 11~+cells and compact(CP) embryos according to the cells number of cleavage embryo. The blastocyst formation rate of subgroups with different cells number in different age groups were compared. There were 2 402 cycles of single blastocyst frozen-thawed transfer(FET),among which <35 years old group and ≥ 35 years old group were divided into 3 subgroups: 4-6 cells, 7-9 cells and ≥10 cells + CP embryo, according to the cells number of Day 3 embryos which the blastocysts derived from. The clinical outcomes of blastocysts which derived from embryos with different cells number and female age were compared. At the same time, the euploid rate of 1 069 blastocysts undergone preimplantation aneuploidy test(PGT-A) was analyzed, including 3 subgroups(4-6 cells, 7-9 cells and ≥ 10+ cells CP embryo) in <35 years old group and ≥ 35 years old group.Results:In <35 years old group and ≥ 35 years old group, the developmental potential of 8 cells was the highest, followed by embryo at CP stage. The cells number of embryos less than 6 is obviously inferior to the other cells number(P<0.05). In <35 years old group, the difference of embryonic development potential was obvious among the different cells number subgroup. The order of the available blastocyst formation rate(from high to low) was: 8 cells >CP embryos >11⁺ cells =9 cells >10 cells =7 cells >6 cells >5 cells =4 cells. In ≥35 years old group, the order was 8 cells = CP embryo >9 cells =7 cells =11⁺ cells =10 cells >6 cells =4 cells >5 cells. The clinical pregnancy rate, live birth rate and euploidy rate in <35 years old group were significantly higher than those in ≥35 years old group(P<0.001). In <35 years old group, the clinical pregnancy rate and live birth rate of blastocysts which derived from Day 3 embryo with 4-6 cells in single FET cycles were significantly lower than those derived from 7-9 cells and ≥10 cells + CP embryo(P<0.05). There was no significant difference in the clinical pregnancy rate and live birth rate among different cells number subgroups in ≥35 years old group(P>0.05). There was no significant difference in euploidy rate among different cells number subgroups in <35 years old group and ≥35 years old group(P>0.05).Conclusions:The cells number of Day 3 embryo at cleavage stage and blastocyst formation in women of different ages show different development rules. In <35 years old group, the difference of developmental potential with different cells number of Day 3 embryos at the cleavage stage is obvious, and the pregnancy outcome of single transferred blastocyst which derived from Day 3 embryo with 4 to 6 cells is lower than that of other cells number subgroups. In ≥35 years old group, the outcome of single blastocyst FET is not affected by the cells number of Day 3 embryo, and a satisfactory pregnancy rate can be maintained when the blastocyst was formed.