Factors Associated with Successful Vaginal Birth After a Primary Cesarean Section in Women with an Optimal Inter-Delivery Interval

Purpose: We sought to determine the success rate of VBAC and factors associated with achieving VBAC at a referral hospital in the Democratic Republic of Congo in women with a subsequent pregnancy greater than or equal to 18 months from their primary cesarean section (CS).

Patients And Methods: Patients were included for participation if they had an inter-delivery interval (IDI) of at least 18 months from their primary CS, accepted TOLAC, and had no contraindications. Information was collected about patients' demographics, obstetric history, and factors impacting their labor process. Descriptive analyses compared patients that had a successful VBAC and those who did not. Univariate and multivariate binary logistic regression models identified factors associated with a successful VBAC.

Results: Among 231 eligible patients who attempted a VBAC, 57.6% (133) achieved VBAC. Participants had a mean age of 29 (SD 6), with the majority having a prior vaginal delivery (68.8%). VBAC was positively associated with a higher Bishop score (AOR 1.12, 95% CI 1.02, 1.23) and a spontaneous labor onset (AOR 3.06, 95% CI 1.52, 6.17). VBAC was negatively associated with a macrosomic fetus (AOR 0.21, 95% CI 0.08, 0.58).

Conclusion: TOLAC results in VBAC more than half the time and is associated with a spontaneous labor onset and a higher Bishop score. Women with a macrosomic fetus were more likely to have an unsuccessful VBAC, resulting in an RCS. An optimal IDI was not enough to ensure a successful VBAC. Upon patients' arrival to the hospital, practitioners should re-evaluate their eligibility to attempt a VBAC based on their Bishop score and if they had a spontaneous labor onset to decrease the health risks of an RCS.