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

描述（由申请人提供）：美国每年有超过300万名孕妇分娩。尽管这种事件频繁发生，但许多方面的劳动管理缺乏证据。第二产程，定义为从宫颈完全扩张到分娩胎儿的间隔，是对母亲和胎儿生理要求最高的产程。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，但在产程第二阶段管理产妇推压的最佳技术尚不清楚。两种最常见的方法包括允许自然下降（延迟推）或在宫颈完全扩张后随着子宫收缩开始推（立即推）。先前比较这些方法的研究报告的结果在对新生儿和母亲的益处和伤害方面是相互矛盾的。尽管有这些数据，延迟推得到了广泛使用，人们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，延迟分娩并没有提高阴道自然分娩率，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已经过时的结果措施，例如使用中盆腔旋转钳。我们的大型观察性研究结果表明，选择延迟分娩比立即分娩的分娩结果更差。缺乏一个现代的，大型的，控制良好的，随机的临床试验来解决这个问题，导致了不确定性，在分娩的第二阶段，哪种技术的产妇推动优化的结果。此外，即刻推压与延迟推压对产妇盆底损伤风险的影响尚不清楚。鉴于美国每天约有11000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，以告知当代分娩第二阶段的产科管理。我们建议进行一项大型、多中心、随机的临床试验，比较未产程妇女在达到完全宫颈扩张时的即刻推术和延迟推术。我们的中心假设是，在产程第二阶段立即推搡可以增加自然阴道分娩，缩短第二阶段持续时间，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入对无产妇女阴道自然分娩率的有效性（主要目标），2)确定立即推入对新生儿复合发病率的影响（次要目标#1），以及3)确定立即推入与延迟推入对产妇盆底发病率的客观和主观测量的影响（次要目标#2）。我们估计，将3184名女性随机化将提供足够的统计能力来检测主要和次要结局的有意义的差异。

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.