title: Service configuration, unit characteristics and variation in intervention rates in a national sample of obstetric units in England: an exploratory analysis.
abstract: OBJECTIVE
  To explore whether service configuration and obstetric unit (OU) characteristics explain variation in OU intervention rates in 'low-risk' women.
  
  
  METHODS
  Ecological study using funnel plots to explore unit-level variations in adjusted intervention rates and simple linear regression, stratified by parity, to investigate possible associations between unit characteristics/configuration and adjusted intervention rates in planned OU births. Characteristics considered: OU size, presence of an alongside midwifery unit (AMU), proportion of births in the National Health Service (NHS) trust planned in midwifery units or at home and midwifery 'under' staffing.
  
  
  METHODS
  36 OUs in England.
  
  
  METHODS
  'Low-risk' women with a 'term' pregnancy planning vaginal birth in a stratified, random sample of 36 OUs.
  
  
  METHODS
  Adjusted rates of intrapartum caesarean section, instrumental delivery and two composite measures capturing birth without intervention ('straightforward' and 'normal' birth).
  
  
  RESULTS
  Funnel plots showed unexplained variation in adjusted intervention rates. In NHS trusts where proportionately more non-OU births were planned, adjusted intrapartum caesarean section rates in the planned OU births were significantly higher (nulliparous: R(2)=31.8%, coefficient=0.31, p=0.02; multiparous: R(2)=43.2%, coefficient=0.23, p=0.01), and for multiparous women, rates of 'straightforward' (R(2)=26.3%, coefficient=-0.22, p=0.01) and 'normal' birth (R(2)=17.5%, coefficient=0.24, p=0.01) were lower. The size of the OU (number of births), midwifery 'under' staffing levels (the proportion of shifts where there were more women than midwives) and the presence of an AMU were associated with significant variation in some interventions.
  
  
  CONCLUSIONS
  Trusts with greater provision of non-OU intrapartum care may have higher intervention rates in planned 'low-risk' OU births, but at a trust level this is likely to be more than offset by lower intervention rates in planned non-OU births. Further research using high quality data on unit characteristics and outcomes in a larger sample of OUs and trusts is required.
authors.affiliation: National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Rowe
authors.affiliation: National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: John
authors.initials: J
authors.lastname: Townend
authors.affiliation: National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK Institute for Women's Health, University College London, London, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Brocklehurst
authors.affiliation: National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: Marian
authors.initials: M
authors.lastname: Knight
authors.affiliation: Centre for Maternal and Child Health Research, City University London, London, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Macfarlane
authors.affiliation: Centre for Maternal and Child Health Research, City University London, London, UK.
authors.forename: Christine
authors.initials: C
authors.lastname: McCourt
authors.affiliation: NCT, London, UK.
authors.forename: Mary
authors.initials: M
authors.lastname: Newburn
authors.affiliation: National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: Maggie
authors.initials: M
authors.lastname: Redshaw
authors.affiliation: Division of Women's Health, King's College London, London, UK.
authors.forename: Jane
authors.initials: J
authors.lastname: Sandall
authors.affiliation: The Royal College of Midwives, London, UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Silverton
authors.affiliation: National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hollowell
mesh_terms: D000328:Adult; D016550:Birthing Centers / Q000458:organization & administration*; D036861:Delivery, Obstetric / Q000379:methods*; D004739:England; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D010347:Patient Care Planning; D011247:Pregnancy; D011256:Pregnancy Outcome; D011295:Prenatal Care / Q000458:organization & administration*
keywords: Obstetrics