Increased intravascular coagulation associated with pregnancy.

Based on an increased turnover of the hemostatic system, it is believed that pregnancy is associated with "hypercoagulability." However, this hypothesis is based primarily on the measurement of specific coagulation factors or functional tests reflecting hemostatic activity in vitro. Using recent technological advances, we determined the effect of pregnancy on hemostasis in vivo by measuring 11 specific hemostatic indices simultaneously in 28 healthy pregnant women and in 24 nonpregnant female controls. Significant increases were found in fibrinopeptide A (P less than .01), beta thromboglobulin (P less than .001), platelet factor 4 (P less than .02), and fibrin(ogen) degradation products (P less than .001), suggesting increased platelet turnover, clotting, and fibrinolysis. This state of compensated, accelerated intravascular coagulation may be necessary for maintenance of the uterine-placental interface and preparation for the hemostatic challenge of delivery.