OBJECTIVE: To identify a group of clinical factors that could be used to accurately predict failure in women attempting vaginal birth after cesarean (VBAC).
METHODS: We conducted a planned secondary analysis of a retrospective cohort study of women who were offered VBAC from 1996 to 2000 in 17 community and university hospitals. We collected information about maternal history and outcomes of the index pregnancy. We used univariable and multivariable statistical methods to develop a multivariable prediction model for the outcome of VBAC failure.
RESULTS: A total of 13,706 patients attempted VBAC, with a failure rate of 24.5%. Six variables were significantly associated with VBAC failure in our final logistic regression model: gestational age at delivery, maternal age, maternal race, labor type (spontaneous, augmented, or induced), history of vaginal delivery, and cephalopelvic disproportion or failed induction (combined variable) as prior cesarean indication. The area under the receiver operating characteristics curve is 0.717. To achieve a sensitivity of approximately 75%, a false-positive rate of approximately 40% would result.
CONCLUSION: Our results indicate that significant clinical variables (prelabor and labor) cannot reliably predict VBAC failure.
LEVEL OF EVIDENCE: II
Failure of vaginal birth after cesarean delivery cannot be reliably predicted, even with a multivariable model that incorporates the strongest risk factors.
From the Departments of Obstetrics and Gynecology, 1University of Pennsylvania Health System, Philadelphia, Pennsylvania, and 2 Washington University, St. Louis, Missouri.
See related editorial on page 796.
This study was supported by a grant from the National Institute of Child Health and Human Development (NICHD) (RO1HD 35631 to G.A.M.). Dr. Macones is a recipient of a Mid-Career Award in Patient-Oriented Research (K24 HD 4537328), which partially supported this work, and Dr. Peipert is a recipient of a K24 grant from NICHD (K24 HD01298), which partially supports this work.
Corresponding author: Sindhu K. Srinivas, MD, University of Pennsylvania Medical Center, 2000 Courtyard Building, 3400 Spruce Street, Philadelphia, PA 19104; e-mail: firstname.lastname@example.org.