title: Origin and levels of circulating microparticles in normal pregnancy: A longitudinal observation in healthy women.
abstract: OBJECTIVE
  Microparticles (MP) are actively involved in the hypercoagulable state reported both in normal pregnancies and in pregnancy diagnosed with placenta-mediated complications. In this study the origin and the levels of plasma MP as well as MP activity were evaluated in a group of healthy women during the three trimesters of a normal pregnancy.
  
  
  METHODS
  Seventy-five healthy normotensive pregnant women were enrolled and blood samples were prospectively collected at three different time points corresponding to 1st trimester, 2nd trimester, 3rd trimester of pregnancy. A group of age- matched healthy non-pregnant women acted as controls. Both standard clotting parameters and MP of different origin were measured. MP were identified by size and annexin V- FITC labelling using flow-cytometer. MP subtypes were identified using specific monoclonal antibodies. Procoagulant activity of MP was assessed using the STA® Procoag PPL assay.
  
  
  RESULTS
  The levels of total, platelet-, endothelial-, leukocyte-derived and tissue factor-bearing MP, as well as the MP procoagulant activity, in non-complicated pregnancy were higher in the 1st trimester as compared to non-pregnant age-matched women. Regardless of the origin, MP levels gradually increase during pregnancy, with the highest values reached in the 3rd trimester.
  
  
  CONCLUSIONS
  MP levels gradually increase during normotensive pregnancy. All types of MP including TF+ present with the highest levels in the 3rd trimester. MP convey prothrombotic and proinflammatory antigens already from the first trimester of normal pregnancy. This may contribute to the global hypercoagulable state observed, particularly in the last months of pregnancy, also in healthy women.
authors.affiliation: Department of Medicine, 5th Chair of Internal Medicine, Thrombophilia and Hemophilia Center, University of Padua , Italy.
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Radu
authors.forename: Elena
authors.initials: E
authors.lastname: Campello
authors.forename: Luca
authors.initials: L
authors.lastname: Spiezia
authors.forename: Sonila
authors.initials: S
authors.lastname: Dhima
authors.forename: Silvia
authors.initials: S
authors.lastname: Visentin
authors.forename: Sabrina
authors.initials: S
authors.lastname: Gavasso
authors.forename: Barry
authors.initials: B
authors.lastname: Woodhams
authors.forename: Erich
authors.initials: E
authors.lastname: Cosmi
authors.forename: Paolo
authors.initials: P
authors.lastname: Simioni
mesh_terms: D000328:Adult; D001777:Blood Coagulation / Q000502:physiology*; D016022:Case-Control Studies; D055252:Cell-Derived Microparticles / Q000378:metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D007962:Leukocytes / Q000166:cytology; D008137:Longitudinal Studies; D011247:Pregnancy; D011264:Pregnancy Trimesters / Q000097:blood*; D012016:Reference Values; D013925:Thromboplastin / Q000378:metabolism
chemical_list: D013925:Thromboplastin
keywords: Coagulation and atherothrombosis; flow cytometry; gynecology; hematology; laboratory standardization