Predictors of successful vaginal birth after one caesarean section at selected hospitals in Lusaka, Zambia

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Background. Repeat caesarean section (CS) carries an increased risk of both maternal and neonatal morbidity and mortality. Planned vaginal birth after CS (VBAC), with an estimated success rate of 60 - 80%, is clinically safer than elective repeat CS, and also limits the rise in CSs. There is no single generalised validated tool to predict success of VBAC. Objectives. To determine predictors of successful VBAC among mothers with one previous CS at selected hospitals in Lusaka, Zambia. Method. Determination of independent predictors with significant high odds of a successful VBAC among mothers offered a trial of labour (TOL) was conducted in a cross-sectional study. Women with a history of one previous lower-segment CS, who were carrying a singleton fetus and were in established labour or draining amniotic fluid and scheduled for TOL after CS, were included in the study. Convenience sampling was used to enrol 290 participants. Using SPSS version 22, bivariate analysis and logistic regression analysis were used to analyse data. An independent factor associated with successful VBAC and with a p-value <0.05 was considered significant. Results. Of the participants, 236 (81.4%) had a successful vaginal delivery and 54 (18.6%) failed to deliver vaginally and required emergency CS. Key independent predictors of success of VBAC were primary education level (adjusted odds ratio (AOR) 2.21; 95% confidence interval (CI) 1.01 - 4.84), multiparity (AOR 4.81; 95% CI 1.16 - 19.93), previous successful VBAC (AOR 9.94; 95% CI 1.29 - 76.70), inter-delivery interval after the primary CS (AOR 18.54; 95% CI 5.98 - 57.48), a history of fetal distress (AOR 9.33; 95% CI 2.48 - 35.08), malpresentation (AOR 6.13; 95% CI 1.65 - 22.70) or failed induction of labour (AOR 20.52; 95% CI 3.32 - 127.03) as indications for the primary CS, Bishop score (AOR 7.06; 95% CI 1.92 - 25.97), cervical dilation (AOR 11.62; 95% CI 3.86 - 35.03), duration of labour (AOR 20.78; 95% CI 5.62 - 76.80), birthweight (AOR 6.80; 95% CI 3.33 - 13.91) and Apgar score (AOR 28.42; 95% CI 5.67 - 142.38). Conclusion. A combination of independent sociodemographic and obstetric factors that have significant high odds for a good outcome of VBAC could help predict success of delivery in a given population. This information could also aid in counselling mothers on mode of delivery.