title: A new perspective on VBAC: a retrospective cohort study.
abstract: 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.
  
  
  OBJECTIVE
  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?
  
  
  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.
  
  
  CONCLUSIONS
  The maternal and neonatal morbidity associated with VBAC is comparable to primiparous women undergoing a vaginal birth.
  
  
  CONCLUSIONS
  In demonstrating the low relative morbidity in this comparison, these outcomes may aid in counselling women faced with the choice of VBAC versus ERCS.
authors.affiliation: Department of Obstetrics and Gynaecology, Royal Women's Hospital, Flemington Road, Parkville, Victoria 3050, Australia. geniarozen@hotmail.com
authors.forename: Genia
authors.initials: G
authors.lastname: Rozen
authors.forename: Antony M
authors.initials: AM
authors.lastname: Ugoni
authors.forename: Penny M
authors.initials: PM
authors.lastname: Sheehan
mesh_terms: D000328:Adult; D017604:Cesarean Section, Repeat / Q000009:adverse effects / Q000706:statistics & numerical data; D017558:Elective Surgical Procedures / Q000009:adverse effects / Q000706:statistics & numerical data; D005260:Female; D006771:Hospitals, Maternity; D006784:Hospitals, Teaching; D006801:Humans; D015994:Incidence; D008423:Maternal Age; D009017:Morbidity; D007744:Obstetric Labor Complications / Q000517:prevention & control; D006473:Postpartum Hemorrhage / Q000453:epidemiology; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D014597:Uterine Rupture / Q000453:epidemiology; D016064:Vaginal Birth after Cesarean / Q000009:adverse effects / Q000706:statistics & numerical data; D055815:Young Adult