NEONATAL NUCLEATED RED-BLOOD-CELL COUNTS IN SMALL-FOR-GESTATIONAL-AGEFETUSES WITH ABNORMAL UMBILICAL ARTERY DOPPLER STUDIES

OBJECTIVE: The presence of elevated nucleated red blued cell counts in neonatal blood has been associated with fetal hypoxia. We sought to d etermine whether small-for-gestational-age fetuses with abnormal umbil ical artery Doppler velocity waveforms have elevated nucleated red blo od cell counts. STUDY DESIGN: Hospital charts of neonates with the dis charge diagnosis of small for gestational age (birth weight <10th perc entile) who were delivered between October 1988 and June 1995 were rev iewed for antepartum testing, delivery conditions, and neonatal outcom e. We studied fetuses who had an umbilical artery systolic/diastolic r atio within 3 days of delivery and a complete blood cell count on the first day of life. Multiple gestations, anomalous fetuses, and infants of diabetic mothers were excluded. Statistical analysis included the Student t test, chi(2) analysis, analysis of variance, and simple and stepwise regression. RESULTS: Fifty-two infants met the inclusion crit eria. Those with absent or reversed end-diastolic velocity (n = 19) ha d significantly greater nucleated red blood cell counts than did those with end-diastolic velocity present (n = 33) (nucleated red blood cel ls/100 nucleated cells +/- SD: 135.5 +/- 138 vs 17.4 +/- 23.7, p < 0.0 001). These infants exhibited significantly longer time intervals for clearance of nucleated red blood cells from their circulation (p < 0.0 001). They also had lower birth weights (p < 0.05), lower initial plat elet count (p = 0.0006), lower arterial cord blood pH (p < 0.05), high er cord blood base deficit (p < 0.05), and an increased likelihood of cesarean section for ''fetal distress'' (p < 0.05). Multivariate analy sis demonstrated that absent or reversed end-diastolic velocity (p < 0 .0001) and low birth weight (p < 0.0001) contributed to the elevation of the nucleated red blood cell count, whereas gestational age at deli very was not a significant contributor. CONCLUSION: We observed signif icantly greater nucleated red blood cell counts and lower platelet cou nts in small-for-gestational-age fetuses with abnormal umbilical arter y Doppler studies. This may suggest that antenatal thrombotic events l ead to an increased placental impedance. Fetal response to this chroni c condition may result in an increased nucleated red blood cell count.