title: Induction of labor and risk of postpartum hemorrhage in low risk parturients.
abstract: OBJECTIVE
  Labor induction is an increasingly common procedure, even among women at low risk, although evidence to assess its risks remains sparse. Our objective was to assess the association between induction of labor and postpartum hemorrhage (PPH) in low-risk parturients, globally and according to its indications and methods.
  
  
  METHODS
  Population-based case-control study of low-risk women who gave birth in 106 French maternity units between December 2004 and November 2006, including 4450 women with PPH, 1125 of them severe, and 1744 controls. Indications for labor induction were standard or non-standard, according to national guidelines. Induction methods were oxytocin or prostaglandins. Multilevel multivariable logistic regression modelling was used to test the independent association between induction and PPH, quantified as odds ratios.
  
  
  RESULTS
  After adjustment for all potential confounders, labor induction was associated with a significantly higher risk of PPH (adjusted odds ratio, AOR1.22, 95%CI 1.04-1.42). This excess risk was found for induction with both oxytocin (AOR 1.52, 95%CI 1.19-1.93 for all and 1.57, 95%CI 1.11-2.20 for severe PPH) and prostaglandins (AOR 1.21, 95%CI 0.97-1.51 for all and 1.42, 95%CI 1.04-1.94 for severe PPH). Standard indicated induction was significantly associated with PPH (AOR1.28, 95%CI 1.06-1.55) while no significant association was found for non-standard indicated inductions.
  
  
  CONCLUSIONS
  Even in low risk women, induction of labor, regardless of the method used, is associated with a higher risk of PPH than spontaneous labor. However, there was no excess risk of PPH in women who underwent induction of labor for non-standard indications. This raises the hypothesis that the higher risk of PPH associated with labor induction may be limited to unfavorable obstetrical situations.
authors: INSERM U953 Epidemiological Research Unit on Perinatal Health and Women's and Children's Health, Université Pierre et Marie Curie Paris6, Paris, France.
authors: Imane
authors: I
authors: Khireddine
authors: Camille
authors: C
authors: Le Ray
authors: Corinne
authors: C
authors: Dupont
authors: René-Charles
authors: RC
authors: Rudigoz
authors: Marie-Hélène
authors: MH
authors: Bouvier-Colle
authors: Catherine
authors: C
authors: Deneux-Tharaux
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007751:Labor, Induced / Q000009:adverse effects*; D036801:Parturition; D011159:Population Surveillance; D006473:Postpartum Hemorrhage / Q000453:epidemiology* / Q000209:etiology*; D011247:Pregnancy; D012306:Risk; D055815:Young Adult
references: J Reprod Med. 2002 Feb;47(2):120-4
references: 11883350
references: J Gynecol Obstet Biol Reprod (Paris). 2006 Jun;35(4):373-87
references: 16940906
references: J Gynecol Obstet Biol Reprod (Paris). 2011 Apr;40(2):87-102
references: 21315522
references: Eur J Obstet Gynecol Reprod Biol. 2009 Oct;146(2):149-51
references: 19747756
references: Obstet Gynecol. 1991 Jan;77(1):69-76
references: 1984230
references: Ann Intern Med. 2009 Aug 18;151(4):252-63, W53-63
references: 19687492
references: Anesth Analg. 2010 May 1;110(5):1368-73
references: 20237047
references: Lancet. 2006 Apr 1;367(9516):1066-1074
references: 16581405
references: J Gynecol Obstet Biol Reprod (Paris). 2003 Nov;32(7):638-46
references: 14699333
references: Am J Obstet Gynecol. 2003 Feb;188(2):497-502
references: 12592262
references: Med Care. 2007 Jun;45(6):505-12
references: 17515777
references: Obstet Gynecol. 2009 Jun;113(6):1313-1319
references: 19461428
references: Obstet Gynecol. 1999 Feb;93(2):271-4
references: 9932568
references: Reprod Sci. 2009 May;16(5):501-8
references: 19164477
references: BMC Public Health. 2011 Apr 13;11 Suppl 3:S5
references: 21501456
references: Bull World Health Organ. 2011 Sep 1;89(9):657-65
references: 21897486
references: Gynecol Obstet Fertil. 2004 Aug;32 Spec No 1:4-22
references: 15597666
references: Am J Obstet Gynecol. 2004 Nov;191(5):1516-28
references: 15547519
references: BJOG. 2008 Sep;115(10):1265-72
references: 18715412
references: Am J Obstet Gynecol. 2009 Sep;201(3):273.e1-9
references: 19733277
references: BMJ Open. 2011 Dec 21;1(2):e000514
references: 22189353
references: Eur J Obstet Gynecol Reprod Biol. 2005 Jun 1;120(2):164-9
references: 15925045
references: Natl Vital Stat Rep. 2010 Aug 9;58(24):1-85
references: 21254725
references: Obstet Gynecol. 2009 Aug;114(2 Pt 1):386-397
references: 19623003
references: Obstet Gynecol. 2010 Sep;116(3):601-605
references: 20733441
references: Cochrane Database Syst Rev. 2003;(4):CD003101
references: 14583960
references: Am J Obstet Gynecol. 2011 Jan;204(1):56.e1-6
references: 21047614
references: Obstet Gynecol. 2011 Mar;117(3):583-587
references: 21343761
references: Acta Obstet Gynecol Scand. 2007;86(6):657-65
references: 17520395
references: J Obstet Gynaecol Can. 2009 Dec;31(12):1124-30
references: 20085677
references: BJOG. 2010 Sep;117(10):1278-87
references: 20573150