Hematological and iron status in infants with Rh hemolytic disease: A prospective cohort study.

Background: Infants with Rh hemolytic disease may have iron overload given the ongoing hemolysis. In these infants, iron supplementation may be unnecessary or potentially even harmful. However, there is a paucity of literature to make evidence-based recommendations.

Methods: All neonates with Rh isoimmunization and evidence of fetal anemia were eligible for inclusion in this cohort study. Primary outcomes were serum ferritin and hemoglobin at birth, 3, 6, 9, and 12 months. Additional outcomes were the requirement of top-up transfusion and iron therapy during infancy. Iron supplementation was given only if ferritin was <30 mcg/L. Subgroup analysis was performed based on receipt of intrauterine transfusion (IUT).

Results: Fifty-Six infants were enrolled (gestation 35 ± 2 weeks, weight 2490 ± 480 g). Thirty-Five neonates (62%) received IUT and 21 (38%) received exchange transfusion. Median ferritin (mcg/L) at birth, three- (n = 46), six- (n = 36), nine- (n = 38), and 12-months (n = 35) were 846 [626, 1433], 695 [263, 1041], 219 [105, 601], 122 [42, 242], and 77 [42, 168], respectively. Concomitant hemoglobin (g/dL) values were 14.3, 9.4, 10.9, 10.9, and 10.7, respectively. Serum ferritin was above age-specific cut-off in 53/56 (95%) infants at birth and remained elevated in 16/35 (46%) at 12 months. Top-up transfusion was required in 26/47 infants (55%). Iron supplementation was started in 14/46 infants (30%). Ferritin and top-up transfusion requirements were significantly higher in infants treated with IUT.

Discussion: Infants with Rh isoimmunization demonstrate hyperferritinemia at birth, which can persist till 12 months, particularly in IUT-treated infants. Routine iron supplementation should be deferred in IUT-treated infants until 12 months.