Frozen versus fresh single blastocyst transfer in ovulatory women: a multicentre, randomised controlled trial

Publication date: Available online 28 February 2019Source: The LancetAuthor(s): Daimin Wei, Jia-Yin Liu, Yun Sun, Yuhua Shi, Bo Zhang, Jian-Qiao Liu, Jichun Tan, Xiaoyan Liang, Yunxia Cao, Ze Wang, Yingying Qin, Han Zhao, Yi Zhou, Haiqin Ren, Guimin Hao, Xiufeng Ling, Junzhao Zhao, Yunshan Zhang, Xiujuan Qi, Lin ZhangSummaryBackgroundElective single embryo transfer (eSET) has been increasingly advocated, but concerns about the lower pregnancy rate after reducing the number of embryos transferred have encouraged transfer of multiple embryos. Extended embryo culture combined with electively freezing all embryos and undertaking a deferred frozen embryo transfer might increase pregnancy rate after eSET. We aimed to establish whether elective frozen single blastocyst transfer improved singleton livebirth rate compared with fresh single blastocyst transfer.MethodsThis multicentre, non-blinded, randomised controlled trial was undertaken in 21 academic fertility centres in China. 1650 women with regular menstrual cycles undergoing their first cycle of in-vitro fertilisation were enrolled from Aug 1, 2016, to June 3, 2017. Eligible women were randomly assigned to either fresh or frozen single blastocyst transfer. The randomisation sequence was computer generated, with block sizes of two, four, or six, stratified by study site. For those assigned to frozen blastocyst transfer, all blastocysts were cryopreserved and a delayed frozen-thawed single blastocyst transfer was done. The primar...
Source: The Lancet - Category: General Medicine Source Type: research