Nucleated red blood cell counts in growth-restricted neonates with absent or reversed-end-diastolic umbilical artery...

To determine the effect of increasing circulatory impairment in fetuses on the neonatal nucleated red blood cell count.

Seventy-seven fetuses with suspected intrauterine growth restriction (abdominal circumference < 5th percentile), subsequent birth weight < 10th percentile for gestational age and abnormal umbilical artery Doppler flow velocity were enrolled in the study. Fetuses were assigned to the following groups on the basis of the last Doppler examination before delivery: group 1, umbilical artery S/D ratio > 2 SD above the gestational age mean, group 2, absent end-diastolic velocity in the umbilical artery, group 3, reversed end-diastolic velocity in the umbilical artery. Neonatal nucleated red blood cells were obtained from the umbilical artery within 1 min after delivery with follow-up examinations until the nucleated red blood cell count was < 5/100 white blood cells. Perinatal and neonatal data were recorded from the charts.

Significantly higher nucleated red blood cell counts [median 144, range 9-964] with lowest birth weights [mean 932 g, range 530 g-2060 g] were detected in group 3 and in group 2 [median 65, range 2-720; mean 1049 g, range 630 g-2110 g] compared to group 1 [median 22, range 2-201; mean 1565 g, range 860 g-2780 g, p < 0.001, respectively]. The persistence of nucleated red blood cells in the neonatal circulation was prolonged in group 3 [median 5.2, range 1-13 days] compared to group 2 [median 3.9, range 1-81 and group 1 [median 1, range 0-2]. Neonates in group 3 also had decreased platelet counts, hematocrit and hemoglobin values. Cord blood gases showed a significant decrease of arterial and venous pH values in groups 2 and 3 which was accompagnied by a significant decrease in base excess values. Four neonatal deaths, three of them in the reversed-end-diastolic velocity and one in the absent end-diastolic velocity group, occurred. Stepwise regression demonstrated that absent or reversed end-diastolic flow velocities, birth weight, gestational age and arterial base excess contribute significantly to the elevation of the nucleated red blood cell counts.

Increased nucleated red blood cell counts at birth and their longer persistance in the neonatal circulation are associated with antenatal abnormal umbilical artery Doppler studies in growth restricted fetuses. The nucleated red blood cell count might therefore become an additional valuable tool in the diagnosis of growth restricted fetuses who are metabolically compromised.