Maternal and cord blood hemostasis at delivery

Today we known that the coagulation system of the neonate differs in many ways from that of the adult system. We see a general reduction of the coagulation factors II-XIII (except VIII), the fibrinogen and of the coagulation inhibitors ATIII, protein C and heparin cofactor II at the same time. In addition the newborns show different levels of the coagulation factors for premature and full-term infants. This situation necessitates the generation of not one, but several, reference ranges for the various components of the hemostatic system. While the above-mentioned factors of the coagulation and fibrinolytic system of the newborn are well studied, our knowledge of others is still lagging behind that of the adult. That applies to the vWF and PAI and even more to D-Dimer. Our aim was to collect some data for vWF, PAI and D-Dimer to complete the understanding of the physiology of the hemostatic system in the newborn. Therefore we used the blood samples from 59 newborns and their mothers to obtain a number of different components of the coagulation and fibrinolytic system. Besides some rheological parameters (erythrocyte aggregation, plasma viscosity) we measured the aPTT, PT and the plasma levels of ATIII, fibrinogen and protein C (PC). But we paid special attention to the plasma levels of von Willebrand factor (vWF), plasma activator inhibitor (PAI) and D-Dimer. The blood samples were collected from the umbilical cord and the cubital vein of the mother immediately after delivery, anti-coagulated, centrifuged and stored until measurement at -70 degrees C. ATIII, aPTT, PT and fibrinogen were measured by the clotting technique test on the Chromotimer (Behring, Marburg, Germany). D-Dimer, vWF and protein C were determined with a commercially available ELISA obtained from Boehringer Mannheim (Mannheim, Germany). PAI activity was measured by a two-stage amiolytic method (Behring, Marburg). Besides the known differences of the neonatal hemostatic components to their mothers, such as a prolonged aPTT (52.19 s +/- 13.4 newborn, 35.26 s +/- 4.2 mother), reduced PT (64.34 s +/- 20.15 vs. 91.03 s +/- 1.25), ATIII (83.36% +/- 24.42 vs. 92.58% +/- 11.43) and fibrinogen (156.05 mg/dl +/- 91.68 vs. 344 mg/dl +/- 55.25), we found some peculiarities. The newborns show a clear reduction in the vWF (97.79 ng/ml +/- 36.33 vs. 183.43 ng/ml +/- 16.03) as well as the PAI (0.846 U/ml +/- 1.44 vs. 7.652 U/ml +/- 0.764). D-Dimer levels in the umbilical cord samples (1514.02 ng/ml +/- 953.56) are clearly prolonged in contrast to the maternal levels (740.2 ng/ml +/- 139.68). We were also able to find a difference of these factors related to gestational age. Premature infants showed a clearly higher level of PAI (2.2 U/ml +/- 2.86 vs. 0.69 +/- 1.13; p = 0.0136) compared with full-term infants, as well as significantly lower levels of ATIII (48.8% +/- 23.19 vs. 86.62 +/- 22.04; p = 0.0006) and protein C (25.33% +/- 9.37 vs. 35.73 +/- 7.53; p = 0.0027). D-Dimer, vWF, fibrinogen and the rheological parameters are similar. This seems to show an increased tendency for bleeding with the premature infant. Newborns show a balance of the coagulation system solely on a lower level. This is due to the general reduction of the coagulation factors with a reduction of the coagulation inhibitors at the same time. The physiologically low level of the vitamin K dependent and other coagulation factors and ATIII leads to a prolonged aPTT and reduced PT of the newborn. As well as these differences, known from literature, we found the following specialities: lower vWF and PAI and higher D-Dimer levels of the newborn compared with their mothers.