Fetal hemorheology in normal pregnancy and severe preeclampsia.

Hemorheological parameters were determined in 45 pairs of mothers with severe preeclampsia and their newborns in comparison with 45 women with uncomplicated pregnancies and their newborns. In both groups we investigated red cell deformability, the plasma viscosity, the red cell aggregation (during stasis and low flow), the macromolecules fibrinogen and factor VIIIR:Ag (VWF), and the blood count parameters hemoglobin, hematocrit, white cells, platelets, reticulocytes, MCV, MCHC. Cholesterol and triglycerides were correlated to the parameter of red cell deformability measured as red cell elongation. We found a significant lower plasma viscosity, red cell aggregation, fibrinogen, cholesterol, triglycerides and VWF in cord blood with a close association between plasma viscosity and fibrinogen (r = 0.56, p = 0.001). The red cell deformability measured as red cell elongation was statistically higher in the cord blood compared to the mothers and associated with a higher MCV. In contrast the MCHC values remained unchanged. Hematocrit and hemoglobin in the cord blood were higher than in the mothers. The incidence of fetal hyperviscosity-polycytemia syndrome in women with severe preeclampsia was between 4.7% and 4.9%. An elevated red cell aggregation was found in 2.8% (stasis) and 4.8% (low flow state), respectively. We conclude that in fetal blood the higher hematocrit and the presence of larger red cells do not cause impaired fetal hemorheology.