Vaginal Birth after Caesarean Section: What are the Indications?

Abstract

Objective: this study investigates the extent to which indication for Caesarean section and the availability of perinatal services are associated with the likehood of a woman having a vaginal birth after a previous Caesarean sec tiara (VBAC).Design: this is a retrospective study using both primary data and secondary data obtained from the Hospital Medical Records Institute’s discharge abstract data set. Data were obtained for the 13 Ontario teaching hospitals with obstetrical services. Women with a previous Caesarean section who gave birth in one of the 13 Ontario teaching hospitals with obstetrical services, between October 1992 and September 1993, were classified as very high risk (VHR) or very low risk (VLR) for a repeat Caesarean section. Women were classified as VHR if they had one or more of the 17 diagnoses which a physician panel unanimously agreed were definite indications for Caesarean section. Very low risk women had no indications for Caesarean section other than a uterine scar from a previous Caesarean section. Outcomes of interest were the VBAC rates for VHR and VLR women in hospitals at each of the three perinatal service levels and the trial of labour and VBAC rates for all women with a previous Caesarean section, regardless of risk level, at each perinatal service level.Results: very low risk women who had a trial of labour were significantly more likely to have a VBAC (96.0%) compared to VHR women (46.7%). Hospitals with Level 1 perinatal services had significantly lower trial of labour rates for all women with previous Caesarean section, regardless of risk, compared to Level 2 and Level 3 hospitals (p< 0.001). Women in Level 2 hospitals were significantly more likely to have a trial of labour than were women in Level 3 hospitals (p< 0.05). There was no association between VBAC rates and perinatal service levels.Conclusion: a large proportion of women with a previous Caesarean section and VHR diagnoses, for example, fetal distress, can have VBACs. It also is likely that a large proportion of VLR women in this study who had a repeat Caesarean section without a trial of labour could have had a VBAC. Further investigation is needed into the relative influence of clinical and non-clinical factors on the decision to attempt a vaginal birth after a previous Caesarean section.