Optimizing Management of the Second Stage of Labor: Multicenter Randomized Trial

描述(申请人提供)：美国每年有超过300万孕妇分娩。尽管这一事件频繁发生，但劳工管理的许多方面都缺乏证据。第二产程定义为从宫颈完全扩张到胎儿分娩的间隔时间，是母亲和胎儿生理要求最高的产程。尽管分娩管理可以对分娩方式、新生儿和产妇发病率产生巨大影响，但在第二个分娩阶段管理母体推力的最佳技术尚不清楚。两种最常见的方法包括要么允许自然下降(延迟推)，要么一旦宫颈完全扩张就开始推(立即推)。以前比较这些方法的研究报告的结果在对新生儿和母亲的好处和伤害方面是相互矛盾的。尽管有这些数据，延迟推入获得了广泛的应用，人们认为它可以提高阴道分娩率，降低发病率。相比之下，我们最近的荟萃分析表明，在高质量的试验中，延迟推进并没有提高自然阴道分娩率，而是延长了第二阶段的持续时间。值得注意的是，这项最大规模的试验评估了在美国当代产科中过时的结果衡量标准，例如使用骨盆中旋转钳。我们的大型观察性研究结果表明，选择推迟推与比立即推更糟糕的分娩结局相关。由于缺乏解决这一问题的现代、大型、受控良好的随机临床试验，导致不确定在第二产程中哪种母体推挤技术可以优化结局。此外，即时推力与延迟推力对产妇盆底损伤风险的影响尚不清楚。鉴于美国每天约有11,000名妇女分娩，迫切需要填补这一重要的临床知识缺口，并提供高质量的证据，为当代产科管理人员提供第二阶段分娩的信息。我们提出了一项大型、多中心、随机的临床试验，对足月未分娩的未分娩妇女进行立即和延迟推入，以达到完全的宫颈扩张。我们的中心假设是，在第二产程中立即推进会增加自然阴道分娩，缩短第二产程的持续时间，并减少未分娩妇女的不良新生儿和产妇结局。我们将追求以下具体目标：1)评估完全宫颈扩张时立即推挤对未分娩妇女自然阴道分娩率的有效性(主要目标)，2)确定立即推挤对新生儿综合发病率的影响(次要目标1)，以及3)确定立即推挤与延迟推挤对产妇盆底发病率的主客观指标的影响(次要目标2)。我们估计，对总共3184名妇女进行随机化将提供足够的统计能力，以检测主要和次要结果中有意义的差异。

DESCRIPTION (provided by applicant): Over three million pregnant women labor and give birth in the United States every year. Despite the frequency of this event, many aspects of labor management lack evidence. The second stage of labor, defined as the interval from complete cervical dilation through delivery of the fetus, is the most physiologically demanding period of labor for both the mother and the fetus. Despite the huge impact labor management can have on mode of delivery and neonatal and maternal morbidities, the optimal technique for managing maternal pushing during the second stage of labor is unknown. The two most common approaches involve either allowing for spontaneous descent (delayed pushing) or initiating pushing with uterine contractions once complete cervical dilation occurs (immediate pushing). Prior studies comparing these approaches reported results that are contradictory with regard to benefit and harm to the neonate and mother. Despite these data, delayed pushing gained wide spread use with a perception that it improves rates of vaginal delivery and reduces morbidities. By contrast, our recent meta-analysis demonstrated that among high-quality trials, delayed pushing did not improve the spontaneous vaginal delivery rate, but prolonged second stage duration. Notably, the largest trial evaluated outcome measures that are obsolete in contemporary obstetrics in the United States, such as use of mid-pelvic rotational forceps. Results of our large observational study indicated that selection to delayed pushing is associated with worse labor outcomes than immediate pushing. The lack of a modern, large, well- controlled, randomized clinical trial to address this question has led to uncertainty as to which technique for maternal pushing in the second stage of labor optimizes outcomes. In addition, effects of immediate versus delayed pushing on risk of maternal pelvic floor injury remain unknown. Given that approximately 11,000 women labor and deliver daily in the United States, there is an urgent need to fill this important clinical knowledge gap and provide high-quality evidence to inform contemporary obstetric management of the second stage of labor. We propose a large, multicenter, randomized clinical trial of immediate versus delayed pushing for nulliparous women in labor at term reaching complete cervical dilation. Our central hypothesis is that immediate pushing in the second stage of labor increases spontaneous vaginal delivery, shortens duration of the second stage, and reduces adverse neonatal and maternal outcomes in nulliparous women. We will pursue the following specific aims: 1) Assess the effectiveness of immediate pushing at complete cervical dilation on the rate of spontaneous vaginal delivery in nulliparous women (Primary Aim), 2) Determine the effect of immediate pushing on the rate of neonatal composite morbidity (Secondary Aim #1), and 3) Determine the impact of immediate versus delayed pushing on objective and subjective measures of maternal pelvic floor morbidity (Secondary Aim #2). We estimate that randomizing a total of 3184 women will provide adequate statistical power to detect meaningful differences in the primary and secondary outcomes.