(P10-081-24) Umbilical Cord Plasma Ferritin Concentration as a Proxy Measure of Infant Iron Status: An Exploratory Analysis Among Term and Preterm Infants Born in Vancouver, Canada

Objectives: Low iron status at birth may adversely influence child cognitive and motor development. Prevalence of iron deficiency in pregnancy remains high; however, literature on iron status indicators in infants is limited. The aims of this study were to: 1) summarize cord blood iron biomarker levels, as a proxy measure of infant iron status, from a cohort of births in Vancouver, Canada; and 2) explore maternal and neonatal factors associated with iron status.

Methods: Cord blood specimens (n=46) were obtained from the BC Children’s Hospital BioBank. The primary outcome was cord plasma ferritin concentration, measured using sandwich-ELISA. Predictors of interest included maternal age, gestational age (stratified by preterm vs. term delivery), and infant sex. Multivariable quantile regression was performed to quantify the association between predictors of interest and outcome.

Results: Median (IQR) maternal age and gestational age at delivery was 33.5 (29.3–35.8) years and 36.5 (30–39) weeks, respectively, and 44% of infants were female. Median (IQR) cord plasma ferritin was 100.4 (75.7–128.9) µg/L, and only one infant had a ferritin < 30 µg/L. Among preterm deliveries, a one week increase in gestational age at delivery was associated with a 8.41 (95% CI [0.88, 12.1]) µg/L increase in median cord ferritin. Interestingly, among term deliveries, a negative trend was observed where increasing gestational age was associated with decreasing cord ferritin (-18.8 µg/L per week of gestation [95% CI: -33.7, 14.8]). Female term infants were found to have higher cord ferritin compared to male term infants (β [95% CI]: 35.1 [21.6, 70.0] µg/L).

Conclusions: Most infants had ferritin concentrations >30 µg/L. Consistent with previous literature, cord ferritin increased with gestational age; however, evidence for a non-linear relationship was found, where increasing gestational age beyond 37 weeks was associated with decreased cord ferritin, indicating potential exhaustion of maternal iron stores and decreased placental transfer to the fetus. Sex differences in term infants suggest differences in maternal iron mobilization and fetal iron acquisition dependent on infant sex. Further research is needed to investigate physiological mechanisms behind gestational age- and sex-dependent transfer of iron from mother to fetus.

Funding Sources: Canadian Institutes of Health Research