[Blood coagulation and fibrinolysis in cord blood with reference to birth weight].

To clarify the hemocoagulative and fibrinolytic dynamics of the perinatal period and also to seek the cause of SGA (small for gestational age) baby birth, the coagulation and fibrinolysis of the cord blood were examined, and moreover a comparison with the maternal blood, discussion on the difference in birth weight, and an examination of the difference due to the sex of babies were made in 68 cases with full-term, vaginal, spontaneous delivery, and the following conclusions were reached. In comparison with maternal blood, cord blood significantly showed any of the following: Prolongations of the prothrombin time, and the activated partial thromboplastin time, a decrease in fibrinogen, and a decrease in the platelet aggregation, antithrombin III, and plasminogen. In addition, high values for thromboxane B2 and 6-ketoprostaglandin F1 alpha were observed. In the SGA group, significant decreases were observed in the platelet count, antithrombin III, plasminogen, and alpha 2-plasmin inhibitor as compared with the AGA (appropriate for gestational age) and LGA (large for gestational age) baby groups. No sex difference was observed in the hemocoagulative and fibrinolytic capacities of the cord blood. These hemocoagulative and fibrinolytic capacities, particularly changes in the fibrinolytic system observed in the SGA group, seem to be attributable to chronic DIC (disseminated intravascular coagulation) and mild acidosis due to various stresses during pregnancy and at parturition, in turn due to immaturity of the liver in babies.