Elevation in erythroblast count in maternal blood before the onset of preeclampsia

OBJECTIVE: We recently showed that both maternal and fetal erythroblast counts are elevated in the peripheral blood of pregnant women with preeclampsia. The purpose of this study was to examine whether this elevation actually occurs before the clinical onset of the disorder. STUDY DESIGN: Erythroblasts were enriched and enumerated in 97 maternal blood samples obtained in the second trimester, and results were subsequently correlated with pregnancy outcomes. RESULTS: Significantly higher quantities of erythroblasts (mean, 6041.7 vs 928.9; P = .008) were detected in blood samples obtained from women who later acquired preeclampsia (n = 15) than in blood samples from the control cohort (n = 72). Intrauterine growth restriction (n = 10) was not accompanied by a similar rise in erythroblast count. CONCLUSION: Because a large proportion of the erythroblasts in maternal blood are fetal, our data suggest that fetal-maternal cell traffic is affected early in pregnancies that are later complicated by preeclampsia but not in those affected only by intrauterine growth restriction.