Am J Perinatol 2004; 21(8): 447-453
DOI: 10.1055/s-2004-835961
Copyright © 2004 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA.

Variables Associated with Successful Vaginal Birth after One Cesarean Section: A Proposed Vaginal Birth after Cesarean Section Score

Ron Gonen1 , Ada Tamir2 , Shimon Degani1 , Gonen Ohel1
  • 1Department of Obstetrics and Gynecology, Bnai Zion Medical Center, Haifa, Israel
  • 2Department of Community Medicine and Epidemiology, Faculty of Medicine, Technion, Haifa, Israel
Further Information

Publication History

Publication Date:
06 December 2004 (online)


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 ≤ 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 ≤ 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.


Ron Gonen, M.D. 

Department of Obstetrics and Gynecology, Maternal-Fetal Medicine

Bnai Zion Medical Center, 47 Golomb Street

Haifa, Israel