title: Response to activated protein C decreases throughout pregnancy.
abstract: BACKGROUND
  The possibility that changes in activated protein C anticoagulant activity may contribute to the hemostatic changes associated with pregnancy has been previously investigated, but the results of the studies are still controversial.
  
  
  METHODS
  Nine hundred and sixty-one healthy nonpregnant and 711 normal pregnant women who were noncarriers of factor V Leiden at different weeks' gestation were included in a cross-sectional trial. Moreover, the APC ratio was repeatedly measured in 45 women throughout pregnancy. The activated protein C ratio was tested using the modified activated partial thromboplastin time-based assay.
  
  
  RESULTS
  A significantly lower APC ratio was observed at 20-28 and 32-38 (p = 0.0001) weeks' gestation compared with nonpregnant values. The decrease in the APC ratio throughout pregnancy showed a significant trend (p = 0.014). In none of the subjects did the APC ratio reach the cut-off values for APC resistance.
  
  
  CONCLUSIONS
  Our data confirm a reduction in the APC ratio throughout pregnancy. In our series, an APC ratio of less than 2.0 according to the cut-off point of our laboratory).
authors.affiliation: Department of Gynecology and Obstetrics, University Hospital, University of Turin, Italy. chbened@tin.it
authors.forename: Chiara
authors.initials: C
authors.lastname: Benedetto
authors.forename: Luca
authors.initials: L
authors.lastname: Marozio
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Tavella
authors.forename: Vincenza
authors.initials: V
authors.lastname: Maulà
authors.forename: Daniela
authors.initials: D
authors.lastname: Carmignani
authors.forename: Antonella
authors.initials: A
authors.lastname: Curti
mesh_terms: D020016:Activated Protein C Resistance / Q000097:blood; D000328:Adult; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy / Q000097:blood*; D011250:Pregnancy Complications, Hematologic / Q000097:blood; D011486:Protein C / Q000378:metabolism*
chemical_list: D011486:Protein C