BACKGROUND With improvements in in vitro culture techniques there has been a steady shift in practice to transfer embryos at the blastocyst stage (post fertilization day (p.f.d.) 5-7), when embryos reach the endometrial cavity during natural conception. For patients with > 5 zygotes on day 1 of embryo development, fresh blastocyst embryo transfer (ET) increases live birth rates when compared to cleavage stage (p.f.d. 3) transfer. In poorer prognosis patients (≤ 5 zygotes) cleavage stage ET is commonly performed to reduce the risk of cycle cancellation if no embryo survives to the blastocyst stage. However, there is a dearth of randomized controlled trial (RCT) data demonstrating improved live birth rates per cycle for cleavage vs blastocyst stage ET in this subgroup of patients. The hypothesis of the PRECiSE (PooR Embryo Yield Cleavage Stage Versus blaStocyst Embryo Transfer) trial is that blastocyst ET is not inferior to cleavage stage ET with regard to live birth rates per retrieval in poorer prognosis patients. The adoption of routine blastocyst culture for all patients would result in higher rates of single embryo transfers (SET), reduced incidence of multiple pregnancies and simplified laboratory protocols, thereby reducing costs. METHODS/DESIGN Multicenter, non-inferiority randomized controlled trial (RCT) comparing blastocyst to cleavage stage embryo transfer in poorer prognosis patients with ≤5 zygotes on day 1 after fertilization. The primary outcome is live birth per retrieval. Secondary outcomes include: time to pregnancy, clinical pregnancy, ongoing pregnancy, miscarriage and multiple pregnancy rate (per retrieval). This trial will enroll 658 women with ≤5 zygotes on day 1 at 6 IVF centers over the course of 22 months. DISCUSSION If the hypothesis is proven true, the data from this trial may facilitate the adoption of uniform blastocyst culture in all IVF patients. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT03764865. Registered 5 December 2019, Protocol issue date: 4 December 2018, Original.

中文翻译：

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预后不良IVF患者的卵裂期与胚泡期胚胎移植的非劣效性（PRECiSE试验）：一项随机对照试验的研究方案。

背景技术随着体外培养技术的改进，实践中有一个稳定的转变，即当胚胎在自然受孕过程中到达子宫内膜腔时，在胚泡阶段（受精日（pfd）5-7）转移胚胎。对于在胚胎发育第1天有> 5个受精卵的患者，与卵裂期（pfd 3）转移相比，新鲜胚泡胚胎转移（ET）可提高活产率。在预后较差的患者（≤5个受精卵）中，如果没有胚胎存活到胚泡期，通常进行卵裂期ET以减少周期取消的风险。但是，缺乏随机对照试验（RCT）数据，表明该亚组患者卵裂和胚泡期ET的每个周期的活产率提高。PRECiSE（PooR胚胎产率切割阶段与blastocyst胚胎移植）试验的假设是，就预后较差的患者而言，囊胚ET的平均分娩率不低于卵裂期ET。对所有患者采用常规胚泡培养将导致更高的单胚胎移植（SET）率，减少多次怀孕的发生率并简化实验室规程，从而降低成本。方法/设计多中心，非自卑性随机对照试验（RCT），在受精后第1天对≤5受精卵的预后较差的患者进行了胚泡与卵裂期胚胎移植的比较。主要结果是每次检索活产。次要结果包括：怀孕时间，临床妊娠，持续妊娠，流产和多胎妊娠率（每次检索）。该试验将在22个月的时间内在6个试管婴儿中心招募658名≤5受精卵的女性。讨论如果该假说被证明是正确的，则该试验的数据可能有助于所有IVF患者采用统一的胚泡培养。试验注册ClinicalTrials.gov标识符：NCT03764865。协议注册日期为2019年12月5日，2018年12月4日，正本。