title: Revisit of risk factors for major obstetric hemorrhage: insights from a large medical center.
abstract: OBJECTIVE
  To revisit risk factors of major obstetric hemorrhage in a large obstetric center.
  
  
  METHODS
  A retrospective case control study was conducted based on institutional electronic database and blood bank registry of a single center, 2005-2014. The major obstetric hemorrhage event was defined as transfusion of ≥5 red blood cells units within 48 h of birth and compared to matched group (ratio 1:4) based on the time of birth. Multivariable stepwise backward logistic regression models were fitted to determine risk factors for major obstetric hemorrhage. Odds ratio (OR), further evaluated by standard measures of the predictive accuracy of the logistic regression models, C statistics, and associated neonatal adverse outcome are reported.
  
  
  RESULTS
  113,342 women delivered during the study; 122 (0.1 %) women experienced major obstetric hemorrhage. There was one major obstetric hemorrhage fatality (0.8 %). Compared to the controls, we identified historical as well as significant current modifiable risk factors for major obstetric hemorrhage: multifetal pregnancy (OR 3.92; 95 % CI 1.34-11.52; p = 0.013), induction of labor (OR 2.81; 95 % CI 1.22-7.05; p = 0.027), cesarean section (OR 25.56; 95 % CI 12.88-50.75; p < 0.001), and instrumental delivery (OR 6.58; 95 % CI 2.36-18.3; p < 0.001). C statistics of the model for major obstetric hemorrhage prediction was 0.919 (95 % CI 0.890-0.948, p < 0.001).
  
  
  CONCLUSIONS
  Major obstetric hemorrhage is a rare event with potentially modifiable risk factors which represent a platform of interventions for lessening obstetric morbidity.
authors.affiliation: Department of Obstetrics and Gynecology, Shaare Zedek Medical Center, affiliated with the Hebrew University-Hadassah School of Medicine, Jerusalem, 91031, Israel, sarithelman@gmail.com.
authors.forename: Sarit
authors.initials: S
authors.lastname: Helman
authors.forename: Lior
authors.initials: L
authors.lastname: Drukker
authors.forename: Hila
authors.initials: H
authors.lastname: Fruchtman
authors.forename: Alex
authors.initials: A
authors.lastname: Ioscovich
authors.forename: Rivka
authors.initials: R
authors.lastname: Farkash
authors.forename: Tehila
authors.initials: T
authors.lastname: Avitan
authors.forename: Arnon
authors.initials: A
authors.lastname: Samueloff
authors.forename: Sorina
authors.initials: S
authors.lastname: Grisaru-Granovsky
mesh_terms: D001803:Blood Transfusion / Q000706:statistics & numerical data; D016022:Case-Control Studies; D002585:Cesarean Section / Q000009:adverse effects* / Q000706:statistics & numerical data; D036861:Delivery, Obstetric / Q000009:adverse effects* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007044:Hysterectomy; D016015:Logistic Models; D008428:Maternal Mortality; D015999:Multivariate Analysis; D007744:Obstetric Labor Complications / Q000453:epidemiology / Q000209:etiology*; D016017:Odds Ratio; D006473:Postpartum Hemorrhage / Q000453:epidemiology / Q000209:etiology* / Q000628:therapy; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index