Comparison of pregnancy outcomes following transferring one or two embryos in a selected group of infertility patients.

辅助生殖技术（ART）处理的是对相关个人和整个社会至关重要的问题。尽管取得了重大进展，但ART在许多方面仍然非常昂贵。其中一个主要原因是怀孕率相对较低，每次手术平均为25%。对低妊娠率问题的常见反应是将几个胚胎返回子宫。与这种策略相关的困境是多胎妊娠的高风险，这与母亲和胎儿的不良后果有关。与独生子女相比;双胞胎的胎儿、新生儿和围产期死亡率高3-6倍，多胞胎高5-15倍。双胞胎中幸存者的脑瘫发病率高出6倍，三胞胎高出20倍。在ART中，多胎妊娠相关不良结局发生率的增加已有很好的记录。我们提出了一项随机对照研究，以评估单胚胎移植（SET）与双胚胎移植（DET）的比较。多胎妊娠风险高的不孕妇女将被随机分配接受一个或两个胚胎，这是目前通常的治疗方法。然后，我们将研究单胎和多胎妊娠的发生率，以及这组患者的妊娠成功率。该项目对社区的潜在惠益非常巨大，因为它有能力大幅减少多胞胎的数量。患者也将受益于获得更准确的信息，以便在治疗期间做出明智的选择。

Assisted reproductive technology (ART) deals with issues of fundamental importance to individuals involved, and society as a whole. Despite major advances, ART continues to be very costly in many regards. A major reason for this is the relatively low rate of pregnancy, which averages 25% per procedure. The common response to the problem of low pregnancy rates is to return several embryos to uterus. A dilemma associated with this strategy is the high risk of multiple pregnancy, which is associated with adverse consequences for mother and fetus(es). Compared to singleton births; fetal, neonatal, and perinatal mortality rates are 3-6 times higher in twins, and 5-15 times higher in multiple births of a higher order. Cerebral palsy rates among survivors are six times higher in twins and twenty times higher in triplets. The increase in the incidence of adverse outcomes related to multiple pregnancy has been well documented in ART. We propose a randomised controlled study to assess single embryo transfer (SET) compared to double embryo transfer (DET). Infertility women with a high risk of multiple pregnancy will be randomly allocated to receive one or two embryos, which is the usual treatment at present. We shall then examine the rates of single and multiple pregnancies, and the success of those pregnancies in this group of patients. Potential benefits to the community from this project are very substantial, as it has the capacity to substantially reduce the number of multiple births. Patients will also benefit by having more accurate information with which to make an informed choice during treatment.