冻融周期单囊胚移植的影响因素

人类辅助生殖技术的最终目的是让不孕不育夫妇获得一个健康的孩子。多胎妊娠被认为是一种并发症，而不是成功的助孕结果。如何有效避免双胎妊娠同时维持总体妊娠率一直是辅助生殖治疗中面临的重要挑战之一。选择性单囊胚移植是即能降低多胎率又能有效维持总体临床妊娠率的有效手段。胚胎冷冻保存作为人类辅助生殖技术不可缺少的一部分，在增加移植机会、提高每个取卵周期的累积妊娠率、减少卵巢过度刺激等方面起着重要作用。然而，目前关于冻融周期如何降低多胎率的报道甚少，许多问题有待深入研究。

Prognostic factors in vitrified-thawed cycles with single blastocyst transfer

Objective： To explore the feasibility and the prognostic factors of single blastocyst transfer in vitrified thawed cycles. Methods： Three hundred and seventeen vitrified-thawed cycles with single blastocyst transfer were an- alyzed retrospectively in our reproductive center between August 2009 and December 2010. Clinical out- comes were analyzed according to maternal age, endometrial thickness, blastocyst quality and the methods of fertilization. Results： There were no significant differences between the two methods of fertilization in survival rate of thawed blastocysts and early miscarriage rate （P〉0.05）. The implantation rate and pregnancy rate IVF were slightly higher in IVF cycles than in ICSI cycles, but no statistically significant differences were ob- served （P〉0.05）. There was a trend of increase in clinical pregnancy rate as blastocyst quality increased. The clinical pregnancy rate was more than 45%, when the transferred blastocyst quality was ≥ BB, simi- lar to that of fresh cycles. Maternal age was negatively correlated with clinical pregnancy rate. When the age was more than 35 years, the clinical pregnancy rate showed a downtrend. The endometrial thickness did not contribute significantly to clinical pregnancy rate in vitrified-thawed cycles with single blastocyst transferred. Conclusions： Maternal age, blastocyst quality and the methods of fertilization influenced the clinical outcomes of single blastocyst transfer in vitrified-thawed cycles. Single blastocyst transfer should be con- sidered when one blastocyst with quality of ≥ BB is available.