title: Thrombin generation, D-dimer and protein S in uncomplicated pregnancy.
abstract: BACKGROUND
  Gestational age-specific reference values are essential for the accurate interpretation of haemostatic tests during pregnancy.
  
  
  METHODS
  Our 1-year prospective study included 40 healthy pregnant women with a median age of 30 (range 22-40) years; the subjects were followed in order to establish the gestational age dependent values for endogenous thrombin potential (ETP), D-dimer and protein S (activity and free).
  
  
  RESULTS
  During the first trimester 50% of studied women had ETP >100% (reference values out of pregnancy); in the second trimester an ETP over 100% was observed in all women; ETP values remained unchanged during the third trimester. In the first trimester, the median D-dimer concentration of 0.30 mg/L, in the second 0.91 mg/L and in the third of 1.45 mg/L were observed. During the first trimester 14/40 subjects had protein S activity below reference range (<59%, out of pregnancy); the median value of 61.35; interquartile range (IQR) 20.38; in the second 21/37; the median value of 53.1 (IQR 15.65); in the third trimester 28/37 had low level of protein S activity with the median value of 49.0 (IQR 18.8). Free protein S showed a slight decrease from the first trimester; it remained almost stable during the rest of pregnancy, with the equal number of pregnant women with reduced free protein S.
  
  
  CONCLUSIONS
  Related to the gestational age, a significant increase of ETP and D-dimer, from the second trimester was observed; the decrease of protein S was observed already from the early pregnancy, with more pronounced variability of protein S activity.
authors.forename: Mirjana K
authors.initials: MK
authors.lastname: Kovac
authors.forename: Sanja Z
authors.initials: SZ
authors.lastname: Lalic-Cosic
authors.forename: Jelena M
authors.initials: JM
authors.lastname: Dmitrovic
authors.forename: Valentina J
authors.initials: VJ
authors.lastname: Djordjevic
authors.forename: Dragica P
authors.initials: DP
authors.lastname: Radojkovic
mesh_terms: D000328:Adult; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011264:Pregnancy Trimesters / Q000097:blood; D011446:Prospective Studies; D017293:Protein S / Q000032:analysis*; D013917:Thrombin / Q000032:analysis* / Q000096:biosynthesis*; D055815:Young Adult
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; D017293:Protein S; C036309:fibrin fragment D; D013917:Thrombin