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) microg/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 mug/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.