We investigated peripartum maternal red blood cell (RBC) properties in early-onset preeclampsia (PE). Repeated blood samples were taken prospectively for hemorheological measurements at PE diagnosis (n = 13) or during 26–34 weeks of gestation in healthy pregnancies (n = 24), then at delivery, and 72 h postpartum. RBC aggregation was characterized by M index (infrared light transmission between the aggregated RBCs in stasis) and aggregation index (AI—laser backscattering from the RBC aggregates). We observed significantly elevated RBC aggregation (M index = 9.8 vs. 8.5; AI = 72.9% vs. 67.5%; p < 0.001) and reduced RBC deformability in PE (p < 0.05). A positive linear relationship was observed between AI and gestational age at birth in PE by regression analysis (R2 = 0.554; p = 0.006). ROC analysis of AI showed an AUC of 0.84 (0.68–0.99) (p = 0.001) for PE and indicated a cutoff of 69.4% (sensitivity = 83.3%; specificity = 62.5%), while M values showed an AUC of 0.75 (0.58–0.92) (p = 0.019) and indicated a cutoff of 8.39 (sensitivity = 90.9% and specificity = 50%). The predicted probabilities from the combination of AI and M variables showed increased AUC = 0.90 (0.79–1.00) (p < 0.001). Our results established impaired microcirculation in early-onset PE manifesting as deteriorated maternal RBC properties. The longer the pathologic pregnancy persists, the more pronounced the maternal erythrocyte aggregation. AI and M index could help in the prognostication of early-onset PE, but further investigations are warranted to confirm the prognostic role before the onset of symptoms.

Preeclampsia is the leading cause of complicated neonatal adaptation. The present investigation aimed to study the hemorheological factors during the early perinatal period (cord blood, 24 and 72 h after delivery) in newborns of early-onset preeclamptic mothers (n = 13) and healthy neonates (n = 17). Hematocrit, plasma, and whole blood viscosity (WBV), red blood cell (RBC) aggregation, and deformability were investigated. There were no significant differences in hematocrit. WBV was significantly lower in preterm neonates at birth than in the term 24 and 72 h samples. Plasma viscosity was significantly lower in preterm neonates’ cord blood than in healthy controls. RBC aggregation parameters were significantly lower in preterm newborns’ cord blood than in term neonates’ cord blood 24 and 72 h samples. RBC elongation indices were significantly lower in the term group than in preterm neonates 72 h’ sample at the high and middle shear stress range. Changes in the hemorheological parameters, especially RBC aggregation properties, refer to better microcirculation of preterm neonates at birth, which could be an adaptation mechanism to the impaired uteroplacental microcirculation in preeclampsia.