Predictors of serum ferritin and serum soluble transferrin receptor in newborns and their associations with iron status during the first 2 y of life

Background: Adequate iron status at birth may prevent iron deficiency in early childhood. Objectives: We aimed to identify predictors of serum ferritin (SF) and serum soluble transferrin receptor (sTfR) in healthy newborns and to relate these iron indexes to iron status in the first 2 y of life. Design: Using bivariate correlations and linear regression, we related various factors in pregnancy to SF (n = 363) and sTfR (n = 350) in healthy, term infants. Measurements of cord SF and sTfR were compared with those of SF and sTfR at 6, 12, and 24 mo. All 4 measurements were available for 191 and 169 infants for SF and sTfR, respectively. Results: Geometric mean (and 95% CI) cord SF and sTfR measurements were 159 (148, 171) mu g/L and 7.3 (7.0, 7.6) mg/L, respectively. Cord SF correlated with sTfR (rho = -0.21, P < 0.001). In regression analysis, cord SF correlated with smoking and the use of iron supplements during pregnancy (partial r = -0.12 and 0.16; P < 0.05 for both). Cord sTfR was associated with first trimester BMI, gestational age, and male sex (partial r = 0.30, 0.24, and 0.19, respectively; P < 0.01 for all). Cord SF correlated with SF at 6, 12, and 24 mo (rho = 0.45, 0.31, and 0.16 respectively; P < 0.05 for all). At age 6 mo, 16 of 17 infants with SF < 15 mu g/L were boys. Conclusions: Cessation of smoking and adequate iron prophylaxis during pregnancy may improve iron status in infancy. Cord SF is a predictor of iron status in the first 2 y of life. Boys are at particular risk of low iron status in early infancy.