Objective: To estimate whether a history of a previous successful vaginal birth after cesarean delivery (VBAC) has an effect on a subsequent VBAC attempt.
Methods: A chart review of cases identified from the International Classification of Diseases, 9th Revision (ICD-9) codes and cases identified in the logbooks on Labor and Delivery yielded 1,216 cases of attempted VBAC from 1996 to 2000. Data gathered from these cases included history of previous successful VBAC. Variables of interest included previous successful normal spontaneous vaginal delivery, history of diabetes, labor induction, and recurrent indication for cesarean delivery.
Results: Of the 336 patients with a history of one or more previous successful VBAC attempts, 94.6% had a subsequent successful VBAC, whereas 70.5% of the remaining 880 patients were successful (P <.001). For those patients with one or more previous successful normal spontaneous vaginal deliveries, 87.8% had a successful VBAC, whereas 75.6% were successful without this history (P =.001). The presence of diabetes and a recurrent indication for cesarean delivery both decreased VBAC success and were independently associated with poor outcome (P <.001). Patients with a history of previous VBAC were 7 times more likely to have a subsequent VBAC success (odds ratio 7.40, 95% confidence interval 4.51-12.16; P <.001). Those with a history of previous normal spontaneous vaginal delivery were not more likely to have a successful VBAC when the other variables were controlled. Induction did not affect VBAC outcome.
Conclusion: A history of a previous successful VBAC increases the likelihood for success with future attempts. Maternal diabetes and history of a recurrent indication for cesarean delivery are poor prognosticators for successful trial of labor.
Level of evidence: II-2