title: The association between ABO blood group and obstetric hemorrhage.
abstract: Whether intra- and early post-partum hemorrhage is influenced by ABO blood groups remains unknown. Therefore, we compared women with O to non-O blood groups with regard to maternal post-partum hemorrhage and transfusion need. This retrospective study was conducted in a single tertiary center between 2005 and 2014. For the purpose of the study, parturients were categorized as O and non-O blood groups. Data included all deliveries but excluded patients with missing blood grouping or hemoglobin values, and/or stillbirth. Drop in hemoglobin was defined as hemoglobin concentration at admission for delivery minus lowest hemoglobin concentration post-delivery. Study outcomes were postpartum hemorrhage, hemoglobin drop >2-7 g/dL inclusive, and packed red blood cells transfusion.
  
  
  METHODS
  descriptive, χ(2) (p < 0.05 significant) and multivariable regression models [odds ratio (OR), 95 % confidence interval (CI), p value]. 125,768 deliveries were included. After multivariable analysis, women with O blood type relative to women with non-O blood type had significantly higher odds of postpartum hemorrhage (OR 1.14; 95 % CI 1.05-1.23, p < 0.001), higher odds of statistically significant hemoglobin decreases of >2, 3, or 4 g/dL (OR 1.07; 95 % CI 1.04-1.11, p < 0.001, OR 1.08; 95 % CI 1.03-1.14, p = 0.002, OR 1.14; 95 % CI 1.05-1.23, p = 0.001; respectively), and higher odds, albeit not statistically significant of 5, 6, or 7 g/dL decreases in hemoglobin (OR 1.13; 95 % CI 1.00-1.29, p = 0.055, OR 1.05; 95 % CI 0.84-1.32, p = 0.66, OR 1.15; 95 % CI 0.79-1.68, p = 0.46; respectively), but no difference in blood products transfusion (OR 1.03; 95 % CI 0.92-1.16, p = 0.58). In conclusion, women with blood type O may be at greater risk of obstetrical hemorrhage.
authors.affiliation: Department of Obstetrics and Gynecology, Shaare Zedek Medical Center, Hebrew University Medical School, 12 Bayit Street, 91031, Jerusalem, Israel.
authors.forename: Lior
authors.initials: L
authors.lastname: Drukker
authors.affiliation: Department of Obstetrics and Gynecology, Shaare Zedek Medical Center, Hebrew University Medical School, 12 Bayit Street, 91031, Jerusalem, Israel. srebnikn@szmc.org.il.
authors.forename: Naama
authors.initials: N
authors.lastname: Srebnik
authors.affiliation: Department of Obstetrics and Gynecology, Shaare Zedek Medical Center, Hebrew University Medical School, 12 Bayit Street, 91031, Jerusalem, Israel.
authors.forename: Deborah
authors.initials: D
authors.lastname: Elstein
authors.affiliation: Department of Obstetrics and Gynecology, Hadassah Medical Center, Hebrew University Medical School, Jerusalem, Israel.
authors.forename: Lorinne
authors.initials: L
authors.lastname: Levitt
authors.affiliation: Department of Obstetrics and Gynecology, Shaare Zedek Medical Center, Hebrew University Medical School, 12 Bayit Street, 91031, Jerusalem, Israel.
authors.forename: Arnon
authors.initials: A
authors.lastname: Samueloff
authors.affiliation: Department of Obstetrics and Gynecology, Shaare Zedek Medical Center, Hebrew University Medical School, 12 Bayit Street, 91031, Jerusalem, Israel.
authors.forename: Rivka
authors.initials: R
authors.lastname: Farkash
authors.affiliation: Department of Obstetrics and Gynecology, Shaare Zedek Medical Center, Hebrew University Medical School, 12 Bayit Street, 91031, Jerusalem, Israel.
authors.forename: Sorina
authors.initials: S
authors.lastname: Grisaru-Granovsky
authors.affiliation: Department of Obstetrics and Gynecology, Shaare Zedek Medical Center, Hebrew University Medical School, 12 Bayit Street, 91031, Jerusalem, Israel.
authors.forename: Hen Y
authors.initials: HY
authors.lastname: Sela
mesh_terms: D000017:ABO Blood-Group System / Q000502:physiology*; D000328:Adult; D017707:Erythrocyte Transfusion / Q000706:statistics & numerical data; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D016017:Odds Ratio; D006473:Postpartum Hemorrhage / Q000097:blood / Q000209:etiology* / Q000276:immunology; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D000017:ABO Blood-Group System; D006454:Hemoglobins
keywords: Anemia; Blood group; Blood transfusion; Delivery; Maternal outcome; Postpartum hemorrhage