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Pregnancy: Coagulation factors

Multiple changes are seen in the coagulation system during pregnancy. The greatest change occurs at term. Overall, pregnancy is a hypercoagulable state. However, the traditional measures of coagulation (PT, aPTT, INR) either do not change or decrease slightly during pregnancy. Platelet counts often decrease secondary to dilutional (increase in plasma volume) and consumptive (from the uteroplacental unit) effects. Rarely does this drop result in clinical significance.

Please see table below for individual factor changes.

Table: Hemostatic Changes in Pregnancy

Table: Hemostatic Changes in Pregnancy


  1. Katz D, Bellin Y. Disorders of Coagulation in Pregnancy. Br J Anaesth. 2015;115:ii75-88. PubMed Link