Applying a Prediction Model for Vaginal Birth after Cesarean to a Latina Inner-City Population.

 The Maternal-Fetal Medicine Units (MFMU) Network developed a prediction model for calculating the likelihood of successful vaginal birth after cesarean (VBAC) in patients undergoing a trial of labor after cesarean (TOLAC). In this prediction model, Latina ethnicity is considered a negative predictive factor for successful VBAC. Subsequent studies have found mixed results regarding VBAC success in Latina ethnicity.  Our aim was to compare the predicted chance of successful VBAC (as calculated using the MFMU prediction model) to actual TOLAC outcomes in a large Latina sample.  We performed a retrospective cohort study of Latinas who underwent TOLAC at our institution from January 1, 2013 to December 31, 2016. The MFMU prediction model was used to calculate each participant's predicted success, and the participants were then categorized into three groups based on predicted success: low (<35%), moderate (35-65%), and high (>65%). The predicted success rates versus actual outcomes were compared among the three groups.  A total of 567 Latinas met inclusion criteria. Successful VBAC occurred in 476 patients (84%). VBAC was achieved in 65.3% of the low predicted success group, 84.4% of the moderate predicted success group, and 91.7% of the predicted high success group. Actual VBAC success rates exceeded the predicted success rates for the low and moderate groups.  Our results question whether Latina ethnicity should continue to be considered a negative predictive factor for VBAC success. Our results also suggest that Latinas with a low predicted VBAC success should not necessarily be discouraged from attempting TOLAC.