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，但劳动管理的许多方面缺乏证据。第二产程，定义为从宫颈完全扩张到胎儿娩出的间隔，是对母亲和胎儿生理要求最高的产程时期。尽管产程管理对分娩方式、新生儿和产妇发病率有巨大影响，但在第二产程期间管理产妇推挤的最佳技术尚不清楚。两种最常见的方法涉及允许自然下降（延迟推送）或一旦宫颈完全扩张就开始子宫收缩（立即推送）。之前比较这些方法的研究报告了关于新生儿和母亲的益处和危害的相互矛盾的结果。尽管有这些数据，延迟推获得了广泛的使用，认为它可以提高阴道分娩率并降低发病率。相比之下，我们最近的荟萃分析表明，在高质量的试验中，延迟推并没有提高自然阴道分娩率，但延长了第二阶段的持续时间。值得注意的是，最大的试验评估了在美国当代产科中过时的结局指标，例如使用中骨盆旋转钳。我们的大型观察性研究结果表明，选择延迟推与更差的分娩结局比立即推。由于缺乏现代的、大型的、对照良好的、随机的临床试验来解决这个问题，导致了在第二产程中哪种产妇推送技术能优化结局的不确定性。此外，立即与延迟推动对产妇骨盆底损伤风险的影响仍然未知。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空白，并提供高质量的证据，以告知当代产科管理第二产程。我们建议进行一项大规模、多中心、随机临床试验，比较足月初产妇在达到完全宫颈扩张时立即和延迟推宫的效果。我们的中心假设是，在第二产程中立即推动增加了自然阴道分娩，缩短了第二产程的持续时间，并减少了未产妇的新生儿和产妇的不良结局。我们将努力实现以下具体目标：1）评估宫颈完全扩张时立即用力对未产妇阴道自然分娩率的有效性（主要目的），2）确定立即推对新生儿复合发病率的影响（第二目标#1），和3）确定立即与延迟推对产妇骨盆底发病率的客观和主观测量的影响（第二个目标#2）。我们估计，对3184名女性进行随机分组将提供足够的统计能力来检测主要和次要结局的有意义差异。

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.