Predictive factors of the success of vaginal birth after cesarean delivery and the importance of high body mass index and increased weight gain during pregnancy

Cesarean section is the most common abdominal operation in the world. Incidence of this procedure has been continuously increased in the past four decades, although VBAC (Vaginal Birth After Cesarean) is proved to be a perfect tool to decrease this tendency. Furthermore, modern obstetrical care is highly affected by the blasting number of overweight and obese people, which increases the proportion of women who will already start their pregnancy with excess weight.
In this study I have investigated whether excessive weight gain during pregnancy or obesity alone should mean any risk regarding successful VBAC, and also looked for predictive factors for VBAC success. At the Department of Obstetrics and Gynecology of the University of Debrecen, Hungary I analyzed the data of births in 2012. Based on the logbooks and the computed database I identified those pregnant women who have met inclusion criteria. Based on the pre-pregnancy body mass index (BMI) patients were divided into the following groups: normal weight (BMI<25), overweight (BMI 25-30) and obese (BMI> 30). Excessive weight gain during pregnancy was defined as weight gain of more than 15 kg.
Based on inclusion criteria, 113 women have attempted vaginal trial of labor. Overall, the VBAC success rate was 67,2% (76/113), which is parallel with the literature data. Following trial of labor, VBAC success rates for each BMI category from less than 25 to greater than 30 were 74%, 57,1%, 46,6%, respectively. VBAC was successful in 60% of the patients when weight gain was more than 15 kg, and 68,3% in those who gained less than 15 kg.
In my study I have pointed out that higher prepragnancy BMI decrease VBAC success. I also found previous successful VBAC as a good predictor for VBAC success.