title: The impact of maternal obesity on intrapartum outcomes in otherwise low risk women: secondary analysis of the Birthplace national prospective cohort study.
abstract: OBJECTIVE
  To evaluate the impact of maternal BMI on intrapartum interventions and adverse outcomes that may influence choice of planned birth setting in healthy women without additional risk factors.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Stratified random sample of English obstetric units.
  
  
  METHODS
  17,230 women without medical or obstetric risk factors other than obesity.
  
  
  METHODS
  Multivariable log Poisson regression was used to evaluate the effect of BMI on risk of intrapartum interventions and adverse maternal and perinatal outcomes adjusted for maternal characteristics.
  
  
  METHODS
  Maternal intervention or adverse outcomes requiring obstetric care (composite of: augmentation, instrumental delivery, intrapartum caesarean section, general anaesthesia, blood transfusion, 3rd/4th degree perineal tear); neonatal unit admission or perinatal death.
  
  
  RESULTS
  In otherwise healthy women, obesity was associated with an increased risk of augmentation, intrapartum caesarean section and some adverse maternal outcomes but when interventions and outcomes requiring obstetric care were considered together, the magnitude of the increased risk was modest (adjusted RR 1.12, 95% CI 1.02-1.23, for BMI > 35 kg/m(2) relative to low risk women of normal weight). Nulliparous low risk women of normal weight had higher absolute risks and were more likely to require obstetric intervention or care than otherwise healthy multiparous women with BMI > 35 kg/m(2) (maternal composite outcome: 53% versus 21%). The perinatal composite outcome exhibited a similar pattern.
  
  
  CONCLUSIONS
  Otherwise healthy multiparous obese women may have lower intrapartum risks than previously appreciated. BMI should be considered in conjunction with parity when assessing the potential risks associated with birth in non-obstetric unit settings.
authors.affiliation: National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK.
authors.forename: J
authors.initials: J
authors.lastname: Hollowell
authors.forename: D
authors.initials: D
authors.lastname: Pillas
authors.forename: R
authors.initials: R
authors.lastname: Rowe
authors.forename: L
authors.initials: L
authors.lastname: Linsell
authors.forename: M
authors.initials: M
authors.lastname: Knight
authors.forename: P
authors.initials: P
authors.lastname: Brocklehurst
mesh_terms: D000328:Adult; D015992:Body Mass Index; D001835:Body Weight; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D009765:Obesity / Q000150:complications / Q000453:epidemiology*; D010298:Parity; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011256:Pregnancy Outcome / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult
keywords: Adverse maternal outcomes; adverse perinatal outcomes; augmentation; caesarean section; instrumental delivery; maternal obesity; maternity unit admission criteria; parity; risk factors
references.citation: Obstet Gynecol. 2003 Jan;101(1):24-7
references.pmid: 12517641
references.citation: J Matern Fetal Neonatal Med. 2005 Mar;17(3):179-85
references.pmid: 16147820
references.citation: Am J Obstet Gynecol. 2007 Feb;196(2):163.e1-5
references.pmid: 17306665
references.citation: BJOG. 2005 Jun;112(6):768-72
references.pmid: 15924535
references.citation: Arch Gynecol Obstet. 2007 Jan;275(1):39-43
references.pmid: 16967276
references.citation: Acta Obstet Gynecol Scand. 2010 Oct;89(10):1248-55
references.pmid: 20809871
references.citation: Diabetes Care. 2012 Apr;35(4):780-6
references.pmid: 22357187
references.citation: BMJ. 2011 Nov 23;343:d7400
references.pmid: 22117057
references.citation: Anesth Analg. 2010 May 1;110(5):1368-73
references.pmid: 20237047
references.citation: Acta Obstet Gynecol Scand. 1999 Oct;78(9):799-802
references.pmid: 10535344
references.citation: BMC Pregnancy Childbirth. 2012 Oct 18;12:112
references.pmid: 23078042
references.citation: Diabetes Care. 2010 Mar;33(3):577-9
references.pmid: 20067952
references.citation: Obstet Gynecol. 2004 Nov;104(5 Pt 1):943-51
references.pmid: 15516383
references.citation: BJOG. 2010 Apr;117(5):575-84
references.pmid: 20089115
references.citation: J Matern Fetal Neonatal Med. 2012 Dec;25(12):2579-82
references.pmid: 22873440
references.citation: Paediatr Perinat Epidemiol. 2004 May;18(3):196-201
references.pmid: 15130159
references.citation: Eur J Obstet Gynecol Reprod Biol. 2009 Aug;145(2):163-6
references.pmid: 19525054
references.citation: Arch Gynecol Obstet. 2011 Oct;284(4):827-36
references.pmid: 21072526
references.citation: Am J Obstet Gynecol. 2011 Sep;205(3):244.e1-8
references.pmid: 21798510
references.citation: Int J Obes Relat Metab Disord. 2001 Aug;25(8):1175-82
references.pmid: 11477502
references.citation: Obes Rev. 2008 Nov;9(6):635-83
references.pmid: 18673307
references.citation: BJOG. 2007 Mar;114(3):343-8
references.pmid: 17261121
references.citation: Obes Rev. 2007 Sep;8(5):385-94
references.pmid: 17716296
references.citation: Am J Obstet Gynecol. 2004 Sep;191(3):969-74
references.pmid: 15467574
references.citation: J Perinatol. 2006 Feb;26(2):85-8
references.pmid: 16407959
references.citation: Acta Obstet Gynecol Scand. 2012 Apr;91(4):483-8
references.pmid: 22356510
references.citation: BJOG. 2006 Oct;113(10):1117-25
references.pmid: 16903839
references.citation: Obes Rev. 2009 Jan;10(1):28-35
references.pmid: 19021871