title: Changes in fibrin D-dimer, fibrinogen, and protein S during pregnancy.
abstract: BACKGROUND
  Pregnancy is a hypercoagulable state with a 5- to 10- fold higher risk of venous thromboembolism. Existing reference intervals for fibrin D-dimer (D-dimer), functional fibrinogen (fibrinogen) and protein S, free antigen (protein S) are based on non-pregnant patients and reference intervals for pregnant patients are warranted. Objectives. The aim of the present study was to contribute to the establishment of reference intervals for D-dimer, fibrinogen and protein S during pregnancy and to discuss the use of the analyses during pregnancy.
  
  
  METHODS
  We included 55 healthy pregnant women in gestational week 11-17, with normal current pregnancy. Blood samples were collected in gestational weeks 11-17, 21-27 and 34-37. The three plasma parameters D-dimer, fibrinogen and protein S were analysed by STA-R Evolution®.
  
  
  RESULTS
  A significant rise in D-dimer was found from first to second trimester (p < 0.0001) and from second to third trimester (p < 0.0001). The level of fibrinogen rose significantly from second to third trimester (p < 0.0001). Protein S showed a statistically significant fall in the level from first to second trimester (p < 0.0001) and remained stable thereafter.
  
  
  CONCLUSIONS
  Changes during pregnancy in plasma D-dimer, protein S and fibrinogen were confirmed. Further clinical studies are needed to clarify a clinical useful cut-off point for D-dimer in pregnancy. We suggest careful attention to a low peripartum fibrinogen, since it indicates an increased bleeding risk. We confirmed an earlier suggested lower cut-off point for protein S, during pregnancy.
authors.affiliation: Department of Clinical Biochemistry, Center of Hemophilia and Thrombosis, Aarhus University Hospital, Skejby, Denmark. anette.tarp.hansen@dadlnet.dk
authors.forename: Anette Tarp
authors.initials: AT
authors.lastname: Hansen
authors.forename: Birgitte Horst
authors.initials: BH
authors.lastname: Andreasen
authors.forename: Jannie Dalby
authors.initials: JD
authors.lastname: Salvig
authors.forename: Anne-Mette
authors.initials: AM
authors.lastname: Hvas
mesh_terms: D001798:Blood Proteins / Q000378:metabolism*; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D006801:Humans; D011247:Pregnancy; D011264:Pregnancy Trimesters / Q000097:blood; D017293:Protein S; D012016:Reference Values
chemical_list: D001798:Blood Proteins; D005338:Fibrin Fibrinogen Degradation Products; C523390:PROS1 protein, human; D017293:Protein S; C036309:fibrin fragment D; D005340:Fibrinogen