Predicting Vaginal Birth after Cesarean Section: A Cohort Study

Abstract

Objective: To develop a model to predict vaginal birth after cesarean (VBAC) in our population and to compare the accuracy of this model to the accuracy of a previously published widely used model. Materials and Methods: Women attempting trial of labor after cesarean delivery (TOLAC) at our institution from January 1, 2000 through May 30, 2010 were evaluated for inclusion. Demographic and clinical data were collected. Associations of these characteristics with VBAC were evaluated with univariate and multivariate logistic regression. We critically compared the accuracy of the resulting model to a previously published widely utilized model for predicting VBAC. Results: A total of 2,635 deliveries with at least 1 prior cesarean delivery were identified. TOLAC was attempted in 599 (22.7%) and resulted in 456 VBACs (76.0%) and 143 repeat cesareans (24.0%). VBAC success was independently associated with age <30 years, a body mass index <30, prior vaginal delivery, prior VBAC, and absence of a recurrent indication for cesarean. This model provided a range of successful probability of VBAC (38-98%) with an area under the receiver operating characteristic curve of 0.723. Conclusions: This study provides an accurate and simple model that can be utilized to guide decisions related to TOLAC.

Trial of labor after cesarean in the low-risk obstetric population: a retrospective nationwide cohort study

“…Rates of VBAC success have consistently been quoted to range between 60 and 80%, with most averaging~70%. 2,5,10,20 Our study noted a significantly lower VBAC success rate of~48.0%, which included deliveries both with and without instrumentation. Some of the best predictors of successful VBAC delivery remain a history of prior successful vaginal delivery, 3,19 and/or prior successful VBAC delivery.…”

Maternal and obstetrical factors associated with a successful trial of vaginal birth after cesarean section

“…In this study, BMI was significantly lower in the successful TOLAC group compared to the unsuccessful group, and the number of women with BMI >25 kg/m 2 was significantly higher in the unsuccessful group; also, mean gestational age was significantly lower in the successful TOLAC group compared to the unsuccessful group, and the number of women admitted in labor with gestation ≥40 weeks was significantly higher in the unsuccessful group. Landon et al (17) reported a significantly lower success rate of vaginal birth after cesarean section (68.4%) in obese (BMI ≥30) than non-obese women (76.9%), and Juhasz et al (18) reported decreasing chances of a successful TOLAC with increasing BMI; also, Tessmer et al (19) concluded that VBAC success was independently associated with age <30 years, body mass index <30, prior vaginal delivery, and prior VBAC. Smith et al (20) concluded that a TOLAC was likely to be unsuccessful at 41 weeks or 42 weeks gestation compared to a TOLAC at 40 weeks, and Coassolo et al (21) reported a 31.3% TOLAC failure rate at 40 weeks or beyond, against 22% in <40 weeks; also, Tita et al (22) concluded that the risks of maternal morbidities and cesarean delivery, but not neonatal morbidity, increased significantly among laboring nulliparous women beyond 39 weeks.…”

Trial of labor after previous cesarean delivery (TOLAC) and association of BMI and previous vaginal delivery with frequency of VBAC

“…A number of risk factors for unsuccessful VBAC are mentioned like induced labor, no previous vaginal birth, body-mass index greater than 30, and previous cesarean section for dystocia [19][20][21][22][23] . A study done on Fourteen thousand five hundred twenty-nine women found out that overall Trial of Labour after one previous cesarean section success rate in obese women (BMI≥30) was lower (68.4%) than in nonobese women (BMI<30) 24 .Similar results were seen in our study.…”