title: Variables associated with successful vaginal birth after one cesarean section: a proposed vaginal birth after cesarean section score.
abstract: The objective of this study was to define the variables associated with vaginal birth after cesarean section (VBAC) and to develop a scoring system for the prediction of successful VBAC. We searched our computerized database for parturients with a history of one low-transverse cesarean section (CS) who were delivered during the year 2000. Variables were categorized according to the time period in which they were obtained: (1) first prenatal visit, (2) at the onset of labor, and (3) during labor. Univariate and multiple stepwise logistic regression models were fitted to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Of the 475 parturients with a history of one previous CS, 136 underwent elective CS and 339 underwent a trial of VBAC, of whom 82% were successful. Of the variables that can be obtained at the onset of labor, five were significantly associated with successful VBAC: abnormal presentation as the indication for the primary CS (OR, 7.4; 95% CI 2.8 to 19.2), a previous VBAC (OR, 7.2; 95% CI, 2.1 to 24.8), cervical dilation (OR, 2.5; 95% CI, 1.3 to 4.9), gestational age < or = 41 weeks (OR, 2.8; 95% CI, 1.1 to 7.1), and lower gestational age at the primary CS (OR, 1.2; 95% CI, 1.02 to 1.4). In the proposed VBAC score, each of the four most significant variables was assigned a score ranging between 0 and 3 based on the probability for VBAC. A score < or = 2 was associated with a success rate of 42%, a score between 3 and 6 was associated with a rate of 81%, and a score between 7 and 10 was associated with a 98% successful VBAC rate (p < 0001). The proposed VBAC score may help obstetricians when counseling their patients regarding the individual likelihood of a successful VBAC.
authors.affiliation: Department of Obstetrics and Gynecology, Bnai Zion Medical Center, Haifa, Israel.
authors.forename: Ron
authors.initials: R
authors.lastname: Gonen
authors.forename: Ada
authors.initials: A
authors.lastname: Tamir
authors.forename: Shimon
authors.initials: S
authors.lastname: Degani
authors.forename: Gonen
authors.initials: G
authors.lastname: Ohel
mesh_terms: D000328:Adult; D016208:Databases, Factual; D003661:Decision Support Techniques; D005260:Female; D006801:Humans; D007557:Israel / Q000453:epidemiology; D016015:Logistic Models; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011247:Pregnancy; D016064:Vaginal Birth after Cesarean / Q000706:statistics & numerical data*