PROS1 and Stroke: In addition to vasoactive changes, pregnancy is a hypercoagulable state characterized by an increase in the level of pro-thrombotic factors and a decrease in anticoagulant factors such as protein S. ICH which can occur in the setting of stroke, rupture of an aneurysm or vascular malformation, or be due to hypertension, PRES, or RCVS, is associated with a mortality rate of around 20% (20).