title: Antenatal fibrinogen concentrations and postpartum haemorrhage.
abstract: BACKGROUND
  It is unclear whether antenatal fibrinogen concentrations are associated with postpartum haemorrhage.
  
  
  METHODS
  This retrospective study included 871 women with a singleton pregnancy but no known risk factors for postpartum haemorrhage, in whom fibrinogen concentration was measured within the 21 days before delivery. Correlation between antenatal fibrinogen concentrations and estimated blood loss was analysed. We tested the hypothesis that the risk of postpartum haemorrhage was higher in women with antenatal fibrinogen concentrations of <3.3 g/L. Postpartum haemorrhage was defined as an estimated blood loss ⩾700 mL following vaginal delivery and ⩾1000 mL following caesarean delivery.
  
  
  RESULTS
  In women delivering vaginally (n=337), estimated blood loss tended to increase with decreasing antenatal fibrinogen concentration (R=-0.107, P=0.05), median fibrinogen concentration was significantly lower in 69 women with postpartum haemorrhage than in 268 women without postpartum haemorrhage (3.93 vs. 4.18 g/L, P=0.025), and postpartum haemorrhage occurred significantly more often in women with fibrinogen concentrations <3.3 g/L than in those with concentrations ⩾3.3 g/L (38% [11/29] vs. 19% [58/308], P=0.018). In women undergoing caesarean delivery (n=534), median fibrinogen concentration did not differ between those who experienced postpartum haemorrhage (n=128) and those who did not (n=406) (4.18 g/L vs. 4.07 g/L, P=0.43). Antenatal fibrinogen concentrations of <3.3g/L were not associated with higher rates of postpartum haemorrhage (26% [11/43] vs. 24% [117/491], P=0.80).
  
  
  CONCLUSIONS
  Antenatal fibrinogen concentration <3.3g/L may be a risk factor for postpartum haemorrhage among women following vaginal delivery.
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan. Electronic address: yamatakashi@me.com.
authors.forename: T
authors.initials: T
authors.lastname: Yamada
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Akaishi
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Oda
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Nishida
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamada
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ishikawa
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Morikawa
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kojima
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Minakami
mesh_terms: D000293:Adolescent; D000328:Adult; D016063:Blood Loss, Surgical; D002585:Cesarean Section; D036861:Delivery, Obstetric; D005260:Female; D005340:Fibrinogen / Q000032:analysis*; D006801:Humans; D006473:Postpartum Hemorrhage / Q000097:blood* / Q000453:epidemiology*; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult
chemical_list: D005340:Fibrinogen
keywords: Caesarean delivery; Fibrinogen; Postpartum haemorrhage; Vaginal delivery