Fetal and Neonatal Reticulocyte Count Response to Intrauterine Transfusion for the Treatment of Red Blood Cell Alloimmunization.

Management of hemolytic disease of the fetus and newborn relies on monitoring of maternal antibody titers, fetal ultrasound, and fetal middle cerebral artery peak systolic velocity studies and is generally treated by intrauterine transfusion (IUT). Few studies have explored fetal and neonate physiological responses to IUT. Our objective was to examine fetal erythropoietic response and to examine neonatal erythropoietic effects after treatment. Thirty-six patients treated from 2005 to 2015 were identified retroactively. The time course of treatment, including gestational age and number of IUT, and timing of delivery were reviewed. Fetal reticulocyte count and neonatal hemoglobin and reticulocyte counts were analyzed for each IUT. For each gestational week, reticulocyte count decreased by ∼8.6% (95% confidence interval [CI]: 5.3-12.0). In the neonatal period, there was significant correlation between hemoglobin at birth and number of transfusions (Spearman correlation 0.473, 95% CI: 0.113-0.715, P =0.01) as well as reticulocyte count at birth and number of transfusions (Spearman correlation: 0.393, 95% CI: 0.058-0.642, P =0.02). IUT appears to have a direct and measurable effect on fetal reticulocyte production which persists in neonates.