title: Selected maternal morbidities in women with a prior caesarean delivery planning vaginal birth or elective repeat caesarean section: a retrospective cohort analysis using data from the UK Obstetric Surveillance System.
abstract: OBJECTIVE
  To conduct a secondary analysis of data from the UK Obstetric Surveillance System (UKOSS) to estimate the rates of specific maternal risks associated with planned vaginal birth after caesarean (VBAC) and elective repeat caesarean section (ERCS).
  
  
  METHODS
  A retrospective cohort analysis using UKOSS data from 4 studies conducted between 2005 and 2012.
  
  
  METHODS
  All hospitals with consultant-led maternity units in the UK.
  
  
  METHODS
  Pregnant women who had a previous caesarean section.
  
  
  METHODS
  Women who had undergone a previous caesarean section were divided into 2 exposure groups: planned VBAC and ERCS. We calculated the incidence of each of the 4 outcomes of interest with 95% CIs for the 2 exposure groups using proxy denominators (total estimated VBAC and ERCS maternities in a given year). Incidences were compared between groups using χ(2) test or Fisher's exact test and risk ratios with 95% CI.
  
  
  METHODS
  Severe maternal morbidities: peripartum hysterectomy, severe sepsis, peripartum haemorrhage and failed tracheal intubation.
  
  
  RESULTS
  The risks of all complications examined in both groups were low. The rates of peripartum hysterectomy, severe sepsis, peripartum haemorrhage and failed tracheal intubation were not significantly different between the 2 groups in absolute or relative terms.
  
  
  CONCLUSIONS
  While the risk of uterine rupture in the VBAC and ERCS groups is well understood, this national study did not demonstrate any other clear differences in the outcomes we examined. The absolute and relative risks of maternal complications were small in both groups. Large epidemiological studies could further help to assess whether the incidence of these rare outcomes would significantly differ between the VBAC and ERCS groups if a larger number of cases were to be examined. In the interim, this study provides important information to help pregnant women in their decision-making process.
authors.affiliation: National Perinatal Epidemiology Unit (NPEU), Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: Manisha
authors.initials: M
authors.lastname: Nair
authors.affiliation: Department of Obstetrics & Gynaecology, Luton and Dunstable University Hospital, Luton, UK.
authors.forename: Kate
authors.initials: K
authors.lastname: Soffer
authors.affiliation: National Perinatal Epidemiology Unit (NPEU), Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: Nudrat
authors.initials: N
authors.lastname: Noor
authors.affiliation: National Perinatal Epidemiology Unit (NPEU), Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: Marian
authors.initials: M
authors.lastname: Knight
authors.affiliation: Department of Obstetrics & Gynaecology, Luton and Dunstable University Hospital, Luton, UK.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Griffiths
mesh_terms: D015992:Body Mass Index; D016022:Case-Control Studies; D017604:Cesarean Section, Repeat / Q000009:adverse effects*; D017558:Elective Surgical Procedures / Q000009:adverse effects; D005260:Female; D006801:Humans; D007044:Hysterectomy / Q000706:statistics & numerical data; D007442:Intubation, Intratracheal / Q000706:statistics & numerical data; D006473:Postpartum Hemorrhage / Q000209:etiology; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors; D018805:Sepsis / Q000209:etiology; D014597:Uterine Rupture / Q000453:epidemiology / Q000209:etiology; D016064:Vaginal Birth after Cesarean / Q000009:adverse effects*
keywords: Elective Repeat Caesarean Section; Failed tracheal intubation; Peripartum haemorrhage; Peripartum hysterectomy; Severe sepsis; Vaginal Birth after Caesarean