目的:寻找体外受精-胚胎移植(IVF-ET)治疗中选择合适时期和高质量囊胚进行移植的依据。方法:回顾性分析行囊胚移植的4 237例患者的临床资料,其中新鲜单囊胚移植1 574例,冻融单囊胚移植854例,新鲜双囊胚移植135例,冻融双囊胚移植1 674例。根据囊胚发育天数和发育阶段分为第5日(D5)早期组、D5扩张组、第6日(D6)早期组和D6扩张组。比较各组临床妊娠率、种植率、妊娠结局和新生儿情况等各项指标。结果:①单囊胚移植:新鲜周期D5扩张组临床妊娠率和种植率显著高于其它组,其活产率显著高于D6早期组和D6扩张组,流产率明显低于D6扩张组(P<0.05);冻融周期D5扩张组具有较高的复苏率、临床妊娠率和种植率显著高于D5早期组和D6早期组(P<0.05);②双囊胚移植:D5移植2枚扩张期囊胚的种植率显著高于D5移植2枚早期囊胚,其他各组间差异无统计学意义(P>0.05);冻融周期D5扩张组移植2枚囊胚种植率最高,且临床妊娠率显著高于D5早期组,而流产率明显低于后者,差异有统计学意义(P<0.05)。结论:对于单囊胚移植和双囊胚移植,无论新鲜周期或冻融周期,D5扩张组囊胚妊娠结局最佳。 OBJECTIVE: To find out the basis for the selection of proper stage and high quality blastocysts for the treatment of IVF-ET. Methods: The clinical data of 4 237 cases of blastocyst transplantation were retrospectively analyzed. Among them, 1 574 cases were fresh single blastocyst transplantation, 854 cases were frozen-thawed single blastocyst transplantation, 135 cases were fresh double blastocyst transplantation, 1 674 cases. According to the number of blastocyst developmental stages and developmental stages, it was divided into early D5 group, D5 dilatation group, D6 early dilation group and D6 dilatation group. Compare the clinical pregnancy rate, implantation rate, pregnancy outcome and neonatal conditions and other indicators. Results: (1) Single blastocyst transplantation: The clinical pregnancy rate and implantation rate in D5 expansion group were significantly higher than those in other groups, and the live birth rate was significantly higher than that in D6 early and D6 dilation groups, and the abortion rate was significantly lower than that in D6 dilation group <0.05). The D5 expansion group had higher recovery rate, clinical pregnancy rate and implantation rate were significantly higher than those in early D5 and early D6 groups (P <0.05). ② Double blastocyst transplantation: The implantation rate of stage blastocysts was significantly higher than that of two blastocysts transplanted from D5. There was no significant difference among the other groups (P> 0.05). The implantation rate of two blastocysts in D5 expansion group was the highest, and clinical pregnancy The rate of abortion was significantly higher than that of the early stage of D5, while the abortion rate was significantly lower than the latter (P <0.05). CONCLUSIONS: For single blastocyst transplantation and double blastocyst transplantation, the blastocyst outcome in D5 dilatation group was the best regardless of the fresh or freeze-thaw cycles.