Do Cord Serum Ferritin Concentrations Serve as an Index of Neonatal Iron Status?

Abstract

Low iron stores at birth have been associated with adverse health outcomes. Although the importance of this issue has been highlighted, few studies have examined the relationship between indicators of iron status and hemoglobin concentrations at birth. To address this issue, we measured a broad panel of iron status indicators and associated regulatory hormones in 471 infants born from two obstetric populations known to be at increased risk of maternal iron deficiency and anemia: pregnant adolescents (n=280) and women with a multiple pregnancy (n=191). Neonatal cord blood and maternal blood samples were obtained at delivery, and used to evaluate concentrations of hemoglobin (Hb), serum iron (Fe), ferritin (SF), soluble transferrin receptor (sTfR), hepcidin, interleukin‐6 (IL‐6), erythropoietin (EPO), folate and vitamin B12. Delivery occurred at average 39 ± 3 weeks of gestation in adolescents, and at 34 ± 3 weeks in women carrying multiples. When analyzed as a whole, cord hepcidin was found to be inversely correlated with hemoglobin (Hb) (p = 0.0134) and with serum iron (p < 0.001), while positively correlated with IL‐6 (p < 0.0001). No significant associations were found between maternal hepcidin concentrations and neonatal markers of Fe status, including cord hepcidin. Despite serving as a marker of iron status in other settings, ferritin concentrations in cord blood were not significantly associated with any of the Fe status indicators evaluated, and were instead inversely associated with Hb (p = 0.0032). Excluding values from neonates with elevated cord IL6 concentrations did not alter these findings. Additionally, no correlation was observed between cord IL‐6 concentrations and Hb. These results challenge the current understanding that serum ferritin can serve as an independent marker of Fe status at birth. Our observations underscore the need for further identification and characterization of biomarkers of fetal and neonatal Fe status, and their relationships with outcomes historically attributed to poor iron status during this developmental time frame.Support or Funding InformationThis work was supported by US Department of Agriculture (USDA) and the Gerber Foundation