In traditional assisted reproductive technology (ART), choosing multiple embryo transfer to get a high clinical pregnancy rate while increasing the risk of multiple pregnancies. Research showed that the single-cleavage embryo transfer could not simultaneously meet the dual requirements of maintaining pregnancy rate and reducing the multiple pregnancy rate.The purpose of this study was to observe the clinical outcome between double cleavage embryo transfers and single blastocyst transfers in fresh cycle through RCT study with GnRH antagonist protocol.

In traditional assisted reproductive technology (ART), choosing multiple embryo transfer to get a high clinical pregnancy rate while increasing the risk of multiple pregnancies. Research showed that in the fresh cleavage embryo transfer cycle, the clinical pregnancy rate increased with the increase of the number of high-quality embryos transferred, and so did the multiple pregnancy rate, suggesting that the single-cleavage embryo transfer could not simultaneously meet the dual requirements of maintaining pregnancy rate and reducing the multiple pregnancy rate. Compared with the embryo at cleavage stage, blastocyst culture is a process of survival of the fittest, which is physiologically more synchronized with endometrial development and can improve embryo implantation rate. The existing clinical research analysis is mostly limited to the down-regulating regimen, while the RCT study of high-quality with GnRH antagonist protocol is few. Therefore, the purpose of this study was to observe the clinical outcome between double cleavage embryo transfers and single blastocyst transfers in fresh cycle through RCT study with GnRH antagonist protocol.