Department of Obstetrics and Gynecology, Okayama University Hospital, 2-5-1 Shikata-cho, Kita-Ku, Okayama City, 700-8558, Okayama Prefecture, Japan.
BMC Pregnancy Childbirth. 2024 Aug 15;24(1):542. doi: 10.1186/s12884-024-06744-0.
Cesarean section (C-section) rates are increasing globally, and repeated C-sections are associated with increased maternal morbidity. Trial of labor after C-section (TOLAC) is an approach to reduce the recurrence of C-sections. However, limited research exists on the impact of cesarean scars on labor duration in TOLAC, considering the termination of labor through C-section and selection bias. This study aimed to investigate the impact of cesarean scars on labor duration in TOLAC participants, accounting for potential confounding factors and biases.
This retrospective cohort study included 2,964 women who attempted vaginal birth at a single center in Japan from 2012 to 2021. The study categorized participants into TOLAC (n = 187) and non-TOLAC (n = 2,777) groups. Propensity scores were calculated based on 14 factors that could influence labor duration, and inverse probability of treatment weighting (IPTW) was applied. Cox proportional hazards regression analysis estimated hazard ratios (HRs) for labor duration, with and without IPTW adjustment. Sensitivity analyses used propensity score matching, bootstrapping, and interval censoring to address potential biases, including recall bias in the reported onset of labor.
The unadjusted HR for labor duration in the TOLAC group compared to the non-TOLAC group was 0.83 (95% CI: 0.70-0.98, P = 0.027), indicating a longer labor duration in the TOLAC group. After adjusting for confounding factors using IPTW, the HR was 0.98 (95% CI: 0.74-1.30, P = 0.91), suggesting no significant difference in labor duration between the groups. Sensitivity analyses using propensity score matching, bootstrapping, and interval censoring yielded consistent results. These findings suggested that the apparent association between TOLAC and longer labor duration was because of confounding factors rather than TOLAC itself.
After adjusting for confounding factors and addressing potential biases, cesarean scars had a limited impact on labor duration in TOLAC participants. Maternal and fetal characteristics may have a more substantial influence on labor duration.
剖宫产率在全球范围内呈上升趋势，而多次剖宫产与产妇发病率增加有关。剖宫产后阴道试产（TOLAC）是一种减少剖宫产复发的方法。然而，考虑到通过剖宫产终止分娩和选择偏倚，关于剖宫产瘢痕对 TOLAC 分娩持续时间的影响的研究有限。本研究旨在探讨剖宫产瘢痕对 TOLAC 参与者分娩持续时间的影响，同时考虑潜在的混杂因素和偏倚。
这是一项回顾性队列研究，纳入了 2012 年至 2021 年期间在日本一家单中心尝试阴道分娩的 2964 名女性。研究将参与者分为 TOLAC（n=187）和非 TOLAC（n=2777）两组。根据可能影响分娩持续时间的 14 个因素计算倾向评分，并应用逆概率处理权重（IPTW）。Cox 比例风险回归分析估计了分娩持续时间的风险比（HR），并进行了 IPTW 调整。敏感性分析使用倾向评分匹配、Bootstrap 法和区间 censoring 来解决潜在的偏倚，包括报告的分娩开始时间的回忆偏倚。
未经调整的 TOLAC 组与非 TOLAC 组之间的分娩持续时间 HR 为 0.83（95%CI：0.70-0.98，P=0.027），表明 TOLAC 组的分娩持续时间更长。使用 IPTW 调整混杂因素后，HR 为 0.98（95%CI：0.74-1.30，P=0.91），表明两组之间的分娩持续时间无显著差异。使用倾向评分匹配、Bootstrap 法和区间 censoring 的敏感性分析得出了一致的结果。这些发现表明，TOLAC 与更长的分娩持续时间之间的明显关联是由于混杂因素，而不是 TOLAC 本身。
在调整混杂因素并解决潜在偏倚后，剖宫产瘢痕对 TOLAC 参与者的分娩持续时间的影响有限。产妇和胎儿特征可能对分娩持续时间有更大的影响。
