BACKGROUND Labor intervention is intended to prevent perinatal morbidity and mortality. Labor durations traditionally defined as 'dystocia' drive primary cesarean birth rates, yet there is mixed evidence about the association between labor duration and poor neonatal outcomes. Using latent class analysis to study unknown patterns of neonatal health can refine understanding of these relationships and effect of labor duration on newborn outcomes. OBJECTIVE The purpose of this study was to 1) identify latent classes of newborn health characteristics, 2) describe pregnancy and labor characteristics of individuals in the classes, including active labor duration, 3) determine probability of class membership (newborn health) using labor duration and associated factors as predictors, and 4) assess direct and indirect effects of labor duration versus chorioamnionitis on neonatal risk. STUDY DESIGN Latent class analysis of 3779 term, cephalic, singleton and non-anomalous maternal/child dyads using prospectively collected, observational data. RESULTS Latent class analysis of 3779 term, cephalic, singleton and non-anomalous maternal/child dyads identified 6 neonatal phenotype classes: 4 (classes 1-4, 92% of the data) with normal neonatal outcomes and 2 (classes 5 and 6) with abnormal neonatal outcomes. Apgar scores were not related to more severe markers of neonatal well-being [NICU admission; morbidity diagnosis; failure to discharge home when parent was discharged]. While median labor duration was longer with classes 5 and 6, the majority had labors in the lower three quartiles. Most births in the longest quartile of labor were associated with healthy newborn outcomes. Chorioamnionitis mediated 26% of the relationship between labor duration and newborn health phenotype. CONCLUSION Neonatal risk may be driven or mediated by several labor and birth factors, many of which are challenging to disaggregate. Prior research presuming longer labor duration as the driver of neonatal risk may have masked other relevant associations. More research regarding physiologic versus pathologic inflammatory and infectious processes during term labor is critical for advancing labor dystocia research and refining intrapartum management. Additional variables strongly correlated with labor dystocia (e.g., fetal malposition) should be examined as potential mediators between longer labor and poor neonatal outcomes.

中文翻译：

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不仅仅是时间的流逝：新生儿健康和活跃的分娩持续时间，绒毛膜羊膜炎的中介作用。


背景 分娩干预旨在预防围产期发病率和死亡率。传统上定义为“难产”的分娩持续时间是初次剖宫产率的驱动力，但关于分娩持续时间与新生儿不良结局之间关联的证据不一。使用潜在类别分析来研究新生儿健康的未知模式可以改进对这些关系和分娩持续时间对新生儿结局影响的理解。目的 本研究的目的是 1） 确定新生儿健康特征的潜在类别，2） 描述类别中个体的怀孕和分娩特征，包括活跃的分娩持续时间，3） 使用分娩持续时间和相关因素作为预测因子确定班级成员身份（新生儿健康）的概率，以及 4） 评估分娩持续时间与绒毛膜羊膜炎对新生儿风险的直接和间接影响。研究设计 使用前瞻性收集的观察数据对 3779 个足月、头、单例和非异常母婴二元组进行潜在类别分析。结果 对 3779 个足月、头、单胎和非异常母/童二组进行潜在类别分析，确定了 6 个新生儿表型类别： 4 个 （1-4 类，92% 的数据） 新生儿结局正常，2 个 （5 级和 6 级） 新生儿结局异常。Apgar 评分与新生儿健康状况的更严重标志物无关 [入住 NICU;发病率诊断;父母出院时未能出院回家]。虽然 5 级和 6 级的劳动时间中位数更长，但大多数的劳动时间在较低的三个四分位数。最长四分位数的大多数分娩与健康的新生儿结局相关。绒毛膜羊膜炎介导了 26% 的产程与新生儿健康表型之间的关系。 结论 新生儿风险可能由多种分娩和出生因素驱动或介导，其中许多因素难以分解。先前的研究假设较长的分娩时间是新生儿风险的驱动因素，可能掩盖了其他相关关联。对足月分娩期间生理与病理炎症和感染过程的更多研究对于推进分娩难产研究和完善产时管理至关重要。应检查与难产密切相关的其他变量（例如，胎位不正），作为延长分娩时间和不良新生儿结局之间的潜在中介。