Background: In the mainland of China, the trial of labor after cesarean section is still a relatively new technique. In this study, we aimed to investigate the effects of labor onset, oxytocin use, and epidural anesthesia on maternal and neonatal outcomes for vaginal birth after cesarean section (VBAC) in a tertiary hospital in China.
Methods: This was a retrospective study carried out on 212 VBAC cases between January 2015 and June 2017 in Beijing Obstetrics and Gynecology Hospital, Capital Medical University. Relevant data were acquired on a form, including maternal age, gravidity and parity, body mass index before pregnancy, weight gain during pregnancy, type of labor onset, gestational age, the use of oxytocin and epidural anesthesia, birth mode, the duration of labor, and neonatal weight. The factors affecting maternal and neonatal outcomes for cases involving VBAC, especially with regards to postpartum hemorrhage (PPH) and fetal distress, were evaluated by univariate analysis and multivariable logistic regression.
Results: Data showed that 36 women (17.0%) had postpartum hemorrhage (PPH) and 51 cases (24.1%) featured fetal distress. Normal delivery took place for 163 infants (76.9%) while 49 infants (23.1%) underwent operative vaginal deliveries with forceps. There were 178 cases (84.0%) of spontaneous labor and 34 cases (16.0%) required induction. Oxytocin was used in 54 cases (25.5%) to strengthen uterine contraction, and 65 cases (30.7%) received epidural anesthesia. The rate of normal delivery in cases involving PPH was significantly lower than those without PPH (61.1% vs. 80.1%; χ2 = 6.07, P = 0.01). Multivariate logistic analysis showed that the intrapartum administration of oxytocin (odds ratio [OR] = 2.47; 95% confidence interval [CI] = 1.07-5.74; P = 0.04) and birth mode (OR = 0.40; 95% CI = 0.18-0.87; P = 0.02) was significantly associated with PPH in VBAC cases. Operative vaginal delivery occurred more frequently in the group with fetal distress than the group without (49.0% vs. 14.9%, χ2 = 25.36, P = 0.00). Multivariate logistic analysis also revealed that the duration of total labor (OR = 1.01; 95% CI = 1.00-1.03; P = 0.04) and the gestational week of delivery (OR = 1.08; 95% CI = 1.05-1.11; P = 0.00) were significantly associated with fetal distress in VBAC.
Conclusions: The administration of oxytocin during labor and birth was identified as a protective factor for PPH in VBAC while birth mode was identified as a risk factor. Finally, the duration of total labor and the gestational week of delivery were identified as risk factors for fetal distress in cases of VBAC. This information might help obstetricians provide appropriate interventions during labor and birth for VBAC.
临产方式、产程中缩宫素使用及分娩镇痛对剖宫产术后阴道分娩母婴结局的影响:一项来自中国三级医院的回顾性研究摘要目的：探讨临产方式、缩宫素及分娩镇痛对剖宫产术后阴道分娩（VBAC）母婴结局的影响。 方法：采用回顾性队列研究分析选取2015年1月至2017年6月在首都医科大学附属北京妇产医院实施剖宫产术后阴道分娩的产妇共212例。采用自制表格收集孕妇年龄、孕产次、孕前体重指数、孕期增重、临产方式、分娩孕周、缩宫素使用、分娩镇痛、分娩方式、产程时限及新生儿体重。采用单因素分析及多因素Logistic回归分析母婴结局如产后出血及胎儿窘迫的危险因素。 结果: 36例（17.0%）发生了产后出血，51例(24.1%)胎儿窘迫。163例（76.9%）自然分娩，49例（23.1%）产钳助产。178例产妇自然临产，占84.0%，引产34例，占16.0%。有54例（25.5%）使用缩宫素加强宫缩，65例（30.7%）使用了分娩镇痛。产后出血中的自然分娩比率明显低于无产后出血组（61.1% vs 80.1%,X2=6.07, P=0.01）。多因素Logistic回归分析显示产程中使用缩宫素和分娩方式与VBAC产后出血相关（OR=2.47, 95% CI: 1.07~5.74, P=0.04; OR=0.40, 95% CI 0.18~0.87, P=0.02）。胎儿窘迫组的产钳助产率明显高于非胎儿窘迫组(49.0% vs 14.9%, X2=25.36, P=0.00)。多因素Logistic回归分析显示总产程及分娩孕周是VBAC胎儿窘迫的影响因素(OR=1.01, 95% CI 1.00~1.03, P=0.04; OR=1.08, 95% CI 1.05~1.11, P=0.00)。 结论：产程中使用缩宫素是VBAC发生产后出血的保护性因素，而分娩方式是VBAC发生产后出血的危险因素。总产程时限及分娩孕周是VBAC胎儿窘迫的危险因素。产科医生应为VBAC提供恰当的产时干预。.
Keywords: Fetal Distress; Postpartum Hemorrhage; Risk Factor; Vaginal Birth after Cesarean Section.