Developing a Pilot Model to Predict Successful Vaginal Birth after Caesarean Section for Hong Kong Chinese women

Abstract

Objectives: To determine the success rate of vaginal birth after Caesarean section (VBAC) and its associated factors in local Chinese women with one previous Caesarean delivery and to develop nomograms to quantify the probability of a successful VBAC in an individual woman.
Methods: All women with a history of a single previous uncomplicated lower segment Caesarean section who underwent a trial of labour at Princess Margaret Hospital between 1 January 2013 and 30 June 2015 were identified. Their demographic data, obstetrics and medical history, as well as intrapartum events were obtained. Univariate analyses and multivariate logistic regression were performed to identify significant predictors of a successful VBAC.
Results: Of 507 women attempted a VBAC, 406 (80.1%) succeeded. Women who had a successful VBAC were more likely to be younger, taller, and have a history of vaginal delivery or previous VBAC. Women with a previous emergency Caesarean delivery, a non-progressive labour as the indication for previous Caesarean delivery (odds ratio [OR]=0.453, 95% confidence interval [CI], 0.271-0.756), a significantly longer labour in the present pregnancy (OR =0.997, 95% CI, 0.996-0.998), the use of Syntocinon (OR =0.227, 95% CI=0.130-0.395), and epidural analgesia were more likely to have a failed VBAC. Based on these factors, two nomograms (one for antepartum and another for intrapartum) were developed to quantify the probability of a successful VBAC in an individual woman.
Conclusion: The success rate of VBAC in this local Chinese cohort was 80.1%. Non-progressive labour as the indication for previous Caesarean delivery was the most significant antepartum predictor for a failed VBAC, whereas the use of Syntocinon was the most significant intrapartum predictor.