Objective The purpose of this study was to examine the influence of obesity on vaginal birth after caesarean section, when body mass index (BMI) was based on the accurate measurement rather than self-reporting of maternal weight and height.

Study design We enrolled women at their convenience after a sonogram confirmed an ongoing singleton pregnancy in the first trimester. Weight and height were measured digitally and BMI calculated. Clinical and demographic details were recorded prospectively.

Results Out of 2300 women enrolled, 2209 subsequently delivered in the hospital a baby weighing 500 g or more. There were 50.5% (n=1161) primigravidas and 49.5% (n=1139) multigravidas. There were 188 women who had a previous delivery by caesarean section. The overall VBAC success rate in labour was 66.9%. Of the women that attempted a vaginal birth after previous caesarean section the success rate was 63.2% in Class 1 obese women and 80.0% in Class 2–3 obese women compared with 71.4% in women in the normal BMI category.

Conclusion Our study showed that successful VBAC rates after one previous caesarean section are similar in obese (BMI>29.9 kg/m²) and non-obese women.