Background: Previous studies assessing the safety of vaginal birth after caesarean section (VBAC) have compared VBAC to elective repeat caesarean section (ERCS), despite the fact that the risks posed by each are considerably different. Explaining the complications of VBAC in a way that is meaningful to women can be challenging, and thus a comparison to a similar group of women who have also not undergone previous vaginal delivery may be a more relevant comparison.
Research question: When counselling women undergoing planned VBAC, should a comparison of outcomes be made to women undergoing ERCS, or is a comparison to other nulliparous women undergoing vaginal birth a more valid comparison in terms of risk outcomes?
Participants and methods: A retrospective cohort study was undertaken comprising a consecutive cohort of 21,389 women who delivered, stratified by Robson's criteria into Robson groups 1-5. Those in Robson groups 6-10 were not included. Demographic data and maternal/neonatal outcomes were reviewed, with main outcome measures comprising uterine rupture, post-partum haemorrhage (PPH), 3rd/4th degree tears and neonatal morbidity.
Results: There was no increase in PPH, vaginal tears or neonatal complications in the VBAC group when compared to Robson groups 1 and 2 (nulliparous women in spontaneous or induced labour, respectively). Uterine rupture rates were low in all groups, with no correlation identified.
Discussion: The maternal and neonatal morbidity associated with VBAC is comparable to primiparous women undergoing a vaginal birth.
Conclusion: In demonstrating the low relative morbidity in this comparison, these outcomes may aid in counselling women faced with the choice of VBAC versus ERCS.
Copyright © 2010 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.