随着辅助生殖技术(ART)的广泛应用,多胎妊娠越来越多,已经成为辅助生殖的一个严重并发症.多胎妊娠可发生流产、胎儿畸形、胎儿宫内生长迟缓、贫血、妊娠高血压综合征、羊水过多、前置胎盘及早产等并发症.减少移植胚胎数目来降低多胎妊娠、同时不影响患者妊娠率是所有辅助生殖技术的目的.为达到此目的,在胚胎移植时必须挑选最具有种植潜能的胚胎.囊胚的形成分为三步:细胞融合、囊胚腔出现和囊胚腔扩张,同时经历了从母体调节向胚胎调节的基因调控转换[1,2].发育潜能差及染色体异常的胚胎在未发育至囊胚时即发育停止,只有质量好的胚胎才有发育至囊胚的潜能[3].因此,囊胚培养可以有效地对胚胎进行筛选,减少移植胚胎的数量,从而提高囊胚的着床率及临床妊娠率.%Since its conception, IVF has rapidly become one of the most successful and widely used techniques in the treatment of infertility. At the beginning of ART, the focus of IVF success was PRs. The transfer of multiple embryos was common practice because of low implantation rates. Twins were regarded as an acceptable consequence of improving ART outcome. However, in recent years, this idea has been challenged, and for good reason. Twin pregnancies come with considerable maternal and fetal risk. Twins are associated with increased risks of preeclampsia, isolated hypertension, preterm labor, and preterm rupture of membranes. Twins have an eightfold increased risk of low birth weight compared to singletons. Our focus needs to shift toward implantation rates and number of blastocysts transferred to properly counsel patients and implement the practice of single blastocyst transfers to the appropriate patient population; thus, reducing our countrys high rate of multiples from IVF. Recent studies have looked at single blastocyst stage transfer in which extending embryo culture to day 5 enhances the likelihood of pregnancy when compared with day 3 cleavage stage embryo transfer without the complication of twin gestations. There are many advantages of blastocyst SET. Blastocyst SET can improve the pregnancy of IVF, reduce mult pregnancies and afford the enough time for PGD. But the potential risks to blastocyst transfer; One is monozygotic twinning. An additional risk inherent to blastocyst cycles is the possibility that no blastocysts will be available for transfer.
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