Fetal hemoglobin-expressing nucleated red blood cell frequencies in pregnancies with intrauterine growth restriction

Abstract

The objective of this study was to examine whether there is a difference in the frequency of fetal erythroblasts in maternal blood in pregnancies with intrauterine growth restriction (IUGR) as compared with normal pregnancies. Nucleated red blood cells (NRBC) were isolated from nine pregnant women with ultrasonically diagnosed IUGR (estimated fetal weight less than the 10th percentile for gestational age) and 11 women with appropriately grown fetuses. The frequency of fetal hemoglobin-expressing NRBC (FHE-NRBC) in maternal blood was evaluated by triple density centrifugation and anti-CD71+ magnetic cell sorting, followed by indirect immunocytochemistry for the detection of gamma-chain fetal hemoglobin. The number of FHE-NRBC in 10 ml maternal blood in the IUGR group was higher than in the control group (454.5 vs 56.7, p<0.05). This difference was even more pronounced when FHE-NRBC frequency was calculated relative to the total CD71+ population of cells. There were 118.9 FHE-NRBC per 10(5) CD71+ cells in IUGR pregnancies as compared with 11.5 cells in the control group (p<0.01). There was no difference in the total mean number of CD71+ mononuclear cells between the two groups. The observed increase in the frequency of fetal cells in the maternal circulation found in IUGR pregnancies may be a result of an increase in total NRBC in the fetal circulation or rather of abnormalities in placental structure. This phenomenon may assist in identifying pregnancies at risk for this complication early in the course of the pregnancy, even before actual growth restriction presents itself ultrasonically.