Objective: To compare the clinical outcomes of one and two blastocysts in the freeze-thaw transplantation cycle. Methods: Totally 3 675 cycles of frozen thawed blastocyst transplantation in Reproductive Medical Center of the Second Nanning People's Hospital from January 2012 to December 2016 were analyzed retrospectively. According to the quantity and quality of transferred blastocysts, all the patient were divided into two groups: (1) one embryo group, including the single excellent group (one high quality blastocyst) and the single non excellent group (one non high quality blastocyst); (2) two embryo groups, including the double excellent group (two high quality blastocysts), the one excellent and one non excellent group (one high quality blastocyst+one non high quality blastocyst), and the two non excellent group (two non high quality blastocysts were transplanted). Then the patients were divided into subgroups according to their ages: less than 35 years old, 35-40 years old and over 40 years old. On this basis, the implantation rate, clinical pregnancy rate, multiple birth rate and live birth rate were compared. Results: (1) The implantation rate, clinical pregnancy rate, multiple birth rate, preterm birth rate and live birth rate were all significantly increased, while the abortion rate was significantly reduced in the double blastocyst group (all P<0.05). (2) In the group of<35 years old, the rates of multiple birth and preterm birth in the double blastocyst group were significantly higher than those in the single optimal group (P<0.01). (3) In the 35-40 years old group, the clinical pregnancy rate, multiple birth rate and live birth rate of the double excellent group were significantly higher than those of the single excellent group (P<0.01); while the clinical pregnancy rate and live birth rate of the one excellent and one non excellent group and the double non excellent group were not significantly different from those of the single excellent group (P>0.05), but the multiple birth rate and preterm birth rate were significantly increased (P<0.01). The clinical pregnancy rate, live birth rate and multiple birth rate of double non optimal group were significantly higher than those of single non optimal group (P<0.01). (4) In the group>40 years old, there were no significant differences in clinical pregnancy rate and live birth rate between the two groups (P>0.05). There were no significant differences in implantation rate, clinical pregnancy rate and live birth rate between double non optimal group and single non optimal group (P>0.05). Conclusion: No matter the age of the patients, if the couple have high quality blastocysts, we should give priority to single high quality blastocyst transplantation; even if they have no high quality blastocysts, we should also consider single blastocyst transplantation, in order to reduce the risk of multiple pregnancy and improve the cumulative live birth rate, so as to improve the pregnancy outcome.
目的： 比较冻融周期中单囊胚与双囊胚移植的妊娠结局。 方法： 回顾性分析2012年1月至2016年12月于南宁市第二人民医院生殖医疗中心行冻融囊胚移植的3 675个周期。根据移植囊胚的数量和质量进行分组：（1）单囊胚组：包含单优组（移植1个优质囊胚）和单非优组（移植1个非优质囊胚）；（2）双囊胚组：包括双优组（移植2个优质囊胚）、单优单非优组（移植1个优质囊胚+1个非优质囊胚）和双非优组（移植2个非优质囊胚）。进一步按患者年龄分层：<35岁、35~40岁和>40岁。比较单囊胚与双囊胚移植的着床率、临床妊娠率、多胎妊娠率、活产率、早产率、流产率的差异。 结果： （1）单囊胚组患者年龄大于双囊胚组［分别为（33.2±4.7）和（31.5±4.3）岁］，两组比较，差异有统计学意义（P<0.05）；两组子宫内膜厚度、人工周期占比均无显著差异（P>0.05）。双囊胚组着床率、临床妊娠率、多胎妊娠率、早产率和活产率均显著高于单囊胚组（P<0.05），而流产率则显著低于单囊胚组（P<0.01）。（2）在<35岁患者中，双囊胚组多胎妊娠率和早产率显著高于单优组（P<0.01），双非优组的临床妊娠率、多胎妊娠率、活产率均显著高于单非优组（P<0.01）。（3）在35~40岁患者中，双优组临床妊娠率、多胎妊娠率、活产率均显著高于单优组（P<0.01）；而单优单非优组和双非优组的临床妊娠率、活产率与单优组无显著差异（P>0.05），多胎妊娠率和早产率却显著增加（P<0.01）。双非优组的临床妊娠率、活产率、多胎妊娠率均显著高于单非优组（P<0.01）。（4）在>40岁患者中，与单优组比较，双优组并未显著提高临床妊娠率和活产率（P>0.05），单优单非优组的着床率和双非优组的临床妊娠率均显著下降（P<0.05）。双非优组与单非优组的着床率、临床妊娠率和活产率无显著差异（P>0.05）。 结论： 无论患者年龄如何，若存在优质囊胚，应优先选择单优质囊胚移植；若无优质囊胚，也应考虑单囊胚移植，以期降低多胎妊娠风险，提高累积活产率，改善妊娠结局。.
Keywords: Blastocyst; Cryopreservation; Embryo transfer; Fertilizatoin in vitro; Pregnancy outcome.