title: Duration of Expulsive Efforts and Risk of Postpartum Hemorrhage in Nulliparous Women: A Population-Based Study.
abstract: OBJECTIVE
  To assess the specific association between the duration of expulsive efforts and the risk of postpartum hemorrhage.
  
  
  METHODS
  Population-based cohort-nested case-control study of nulliparous women delivering vaginally in 106 French maternity units between December 2004 and November 2006, including 3,852 women with PPH (blood loss ≥ 500 mL and/or peripartum Hb decrease ≥ 2 g/dL), 1,048 of them severe (peripartum Hb decrease ≥ 4 g/dL or transfusion of ≥ 2 units of red blood cells), and 762 controls from a representative sample of deliveries without hemorrhage in the same population. The association between duration of expulsive efforts and postpartum hemorrhage was estimated by multilevel logistic regression models adjusted for individual and hospital characteristics.
  
  
  RESULTS
  Median duration of expulsive efforts was 18 minutes among controls, 20 minutes among postpartum hemorrhage and 23 minutes among severe postpartum hemorrhage (p<0.01). Duration of expulsive efforts was significantly, positively, and linearly associated with both postpartum hemorrhage and severe postpartum hemorrhage. After adjustment for other risk factors, every additional 10 minutes of expulsive efforts was associated with about a 10% increase in the risk of postpartum hemorrhage (aOR = 1.11 [1.02-1.21]) and severe postpartum hemorrhage (aOR = 1.14 [1.03-1.27]). Oxytocin during labor, duration of active phase of labor, forceps use, episiotomy, perineal tears, and birth weight were also independently associated with both risks.
  
  
  CONCLUSIONS
  Duration of expulsive efforts was independently associated with postpartum hemorrhage and severe postpartum hemorrhage. Interventions to shorten the duration of this stage, such as oxytocin, forceps, and episiotomy, are also associated with higher risks of postpartum hemorrhage. Beyond duration, other aspects of the management of active second stage should be evaluated as some might allow it to last longer with a minimal increase in postpartum hemorrhage risk.
authors.affiliation: Inserm UMR 1153, Obstetrical, Perinatal and Pediatric Epidemiology Research Team (Epopé), Center for Epidemiology and Statistics Sorbonne Paris Cité, DHU Risks in pregnancy, Paris Descartes University, Paris, France.|Department of Obstetrics and Gynecology, McGill University, Montreal, Canada.|Montreal University Health Center, Montreal, Canada.
authors.forename: Marie-Danielle
authors.initials: MD
authors.lastname: Dionne
authors.affiliation: Inserm UMR 1153, Obstetrical, Perinatal and Pediatric Epidemiology Research Team (Epopé), Center for Epidemiology and Statistics Sorbonne Paris Cité, DHU Risks in pregnancy, Paris Descartes University, Paris, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Deneux-Tharaux
authors.affiliation: Aurore perinatal network, Hôpital de la Croix Rousse, Hospices Civils de Lyon, EA 4129 Université Lyon1, Lyon, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Dupont
authors.affiliation: Department of Obstetrics and Gynecology, McGill University, Montreal, Canada.|Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Canada.
authors.forename: Olga
authors.initials: O
authors.lastname: Basso
authors.affiliation: Aurore perinatal network, Hôpital de la Croix Rousse, Hospices Civils de Lyon, EA 4129 Université Lyon1, Lyon, France.
authors.forename: René-Charles
authors.initials: RC
authors.lastname: Rudigoz
authors.affiliation: Inserm UMR 1153, Obstetrical, Perinatal and Pediatric Epidemiology Research Team (Epopé), Center for Epidemiology and Statistics Sorbonne Paris Cité, DHU Risks in pregnancy, Paris Descartes University, Paris, France.
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Bouvier-Colle
authors.affiliation: Inserm UMR 1153, Obstetrical, Perinatal and Pediatric Epidemiology Research Team (Epopé), Center for Epidemiology and Statistics Sorbonne Paris Cité, DHU Risks in pregnancy, Paris Descartes University, Paris, France.|Port Royal Maternity, Cochin-Broca-Hôtel Dieu Hospital, Assistance Publique Hôpitaux de Paris, Paris Descartes University, Paris, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Le Ray
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D036861:Delivery, Obstetric / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006473:Postpartum Hemorrhage / Q000209:etiology*; D011247:Pregnancy; D012307:Risk Factors