title: Risk factors for uterine atony/postpartum hemorrhage requiring treatment after vaginal delivery.
abstract: OBJECTIVE
  We sought to identify risk factors for uterine atony or hemorrhage.
  
  
  METHODS
  We conducted a secondary analysis of a 3-arm double-blind randomized trial of different dose regimens of oxytocin to prevent uterine atony after vaginal delivery. The primary outcome was uterine atony or hemorrhage requiring treatment. In all, 21 potential risk factors were evaluated. Logistic regression was used to identify independent risk factors using 2 complementary predefined model selection strategies.
  
  
  RESULTS
  Among 1798 women randomized to 10, 40, or 80 U of prophylactic oxytocin after vaginal delivery, treated uterine atony occurred in 7%. Hispanic (odds ratio [OR], 2.1; 95% confidence interval [CI], 1.3-3.4), non-Hispanic white (OR, 1.6; 95% CI, 1.0-2.5), preeclampsia (OR, 3.2; 95% CI, 2.0-4.9), and chorioamnionitis (OR, 2.8; 95% CI, 1.6-5.0) were consistent independent risk factors. Other risk factors based on the specified selection strategies were obesity, induction/augmentation of labor, twins, hydramnios, anemia, and arrest of descent. Amnioinfusion appeared to be protective against uterine atony (OR, 0.53; 95% CI, 0.29-0.98).
  
  
  CONCLUSIONS
  Independent risk factors for uterine atony requiring treatment include Hispanic and non-Hispanic white ethnicity, preeclampsia, and chorioamnionitis.
authors.affiliation: Center for Women's Reproductive Health and the Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Alabama at Birmingham School of Medicine, Birmingham, AL. Electronic address: lwetta@uabmc.edu.
authors.forename: Luisa A
authors.initials: LA
authors.lastname: Wetta
authors.forename: Jeff M
authors.initials: JM
authors.lastname: Szychowski
authors.forename: Samantha
authors.initials: S
authors.lastname: Seals
authors.forename: Melissa S
authors.initials: MS
authors.lastname: Mancuso
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Biggio
authors.forename: Alan T N
authors.initials: AT
authors.lastname: Tita
mesh_terms: D000328:Adult; D036861:Delivery, Obstetric / Q000009:adverse effects*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D016015:Logistic Models; D010120:Oxytocics / Q000008:administration & dosage*; D010121:Oxytocin / Q000008:administration & dosage*; D006473:Postpartum Hemorrhage / Q000188:drug therapy / Q000209:etiology* / Q000517:prevention & control; D011247:Pregnancy; D012307:Risk Factors; D014593:Uterine Inertia / Q000188:drug therapy / Q000209:etiology* / Q000517:prevention & control
chemical_list: D010120:Oxytocics; D010121:Oxytocin
keywords: postpartum hemorrhage; risk factors; uterine atony