Holmberg Lisa, Iorizzo Linda, Zaigham Mehreen
Department of Clinical Sciences Lund, Lund University, Lund, Sweden.
Department of Obstetrics and Gynaecology, Skane University Hospital Lund, Lund, Sweden.
BMC Pregnancy Childbirth. 2025 Aug 8;25(1):825. doi: 10.1186/s12884-025-07917-1.
Prolonged second stage of labor increases the risk of insufficient gas exchange over the placenta to the fetus and risk of birth asphyxia. There are considerable variations in clinical guidelines regarding the recommended duration of pushing during the active second stage of labor. Thus, the aim of this study was to investigate the total duration of the second stage of labor and its association to changes in umbilical cord pH and adverse neonatal outcomes in nulliparous women.
This retrospective, multi-center cohort study was based on data from the Perinatal Revision South Register covering seven maternity units from 1995 to 2015. Nulliparous women with fetuses in cephalic position and complete and validated cord blood pH data were recruited to the study. Logistic regression was used to establish the relationship of duration of pushing, categorized in 60 min increments, with cord blood acidosis (umbilical cord arterial pH < 7.05) and adverse neonatal outcomes, including Apgar score at 5 min, risk for central nervous system (CNS) disease, utilization of continuous positive airway pressure (CPAP), neonatal intensive care unit (NICU) admission and hypoxic ischemic encephalopathy (HIE). The adjusted model adjusted for maternal BMI, gestational duration and birth weight.
A total of 37,008 women were included in the analysis. For every 60 min increase in pushing time, there was a significantly increased adjusted odds ratio (aOR) for umbilical arterial pH < 7.05, aOR = 1.639, (95% CI = 1.418-1.895, P = 0.02), Apgar score < 7 at 5-minutes, aOR = 1.408 (95% CI = 1.082-1.831, P = 0.01), and prevalence of suspected CNS disease, aOR = 1.417, (95% CI = 1.065-1.886, P = 0.02). The use of CPAP, (aOR = 1.215, 95% CI = 0.945-1.561, P = 0.13), NICU admission (aOR = 1.021, 95% CI = 0.890-1.171, P = 0.77), neonatal seizures (aOR = 0.000, P = 0.98) and HIE (aOR = 1.377, 95% CI = 0.416-4.109, P = 0.57) were not associated with increased pushing time.
Using a large, population-based cohort, we found that prolonged active second stage of labor was associated with an increased odds for cord blood acidosis at birth, low Apgar score at 5 min, and suspected CNS-disease in neonates. Efficient and evidence-based time management during the active second stage of labor is therefore crucial for reducing the risk of adverse neonatal outcomes.
第二产程延长会增加经胎盘向胎儿的气体交换不足及出生窒息的风险。关于活跃期第二产程推荐的用力时间，临床指南存在相当大的差异。因此，本研究的目的是调查初产妇第二产程的总时长及其与脐动脉血pH值变化和不良新生儿结局的关联。
这项回顾性、多中心队列研究基于1995年至2015年期间来自围产期修订南方登记处的数据，该登记处涵盖七个产科单位。招募了头位胎儿、有完整且经过验证的脐血pH值数据的初产妇。采用逻辑回归分析以60分钟为增量对用力时间进行分类，确定其与脐血酸中毒（脐动脉血pH值＜7.05）及不良新生儿结局之间的关系，这些不良结局包括5分钟时的阿氏评分、中枢神经系统（CNS）疾病风险、持续气道正压通气（CPAP）的使用情况、新生儿重症监护病房（NICU）入院率及缺氧缺血性脑病（HIE）。校正模型对产妇体重指数、孕周和出生体重进行了校正。
共有37008名女性纳入分析。每增加6分钟的用力时间，脐动脉血pH值＜7.05的校正比值比（aOR）显著增加，aOR = 1.639（95%可信区间[CI] = 1.418 - 1.895，P = 0.02）；5分钟时阿氏评分＜7分，aOR = 1.408（95%CI = 1.082 - 1.831，P = 0.01）；疑似CNS疾病的患病率，aOR = 1.417（95%CI = 1.065 - 1.886，P = 0.02）。CPAP的使用（aOR = 1.215，95%CI = 0.945 - 1.561，P = 0.13）、NICU入院（aOR = 1.021，95%CI = 0.890 - 1.171，P = 0.77）、新生儿惊厥（aOR = 0.000，P = 0.98）及HIE（aOR = 1.377，95%CI = 0.416 - 4.109，P = 0.57）与用力时间增加无关。
通过一项基于大规模人群的队列研究，我们发现活跃期第二产程延长与出生时脐血酸中毒几率增加、5分钟时低阿氏评分及新生儿疑似CNS疾病有关。因此产程活跃期高效且基于证据的时间管理对于降低不良新生儿结局风险至关重要。
