Erythropoietic activity and soluble transferrin receptor level in neonates and maternal blood

Effect of Daily Iron Supplementation on Infantile Iron Homeostasis in Preterm Infants

Objective: The aim of this study was to investigate the effects of unified iron supplementation and identify the factors related to the iron homeostasis among preterm infants. Method: A total of 250 preterm infants were divided into neonatal anemic (NA, n = 154) and non-neonatal anemic group (NNA, n = 96). Iron supplements at a dose of 2 mg/kg per day were given from 40 weeks' gestational age to 6 months. Iron status parameters were measured at 3 and 6 months, respectively. Prevalence of iron deficiency (ID) and iron deficiency anemia (IDA), and the correlated factors were analyzed. Growth and side-effects were monitored. Results: There were no significant differences for the prevalence of ID or IDA between the two groups. Multivariate regression analyses showed that higher Hb at birth and early treatment of blood transfusion reduced the risk of ID/IDA at 3 months (all p < 0.05); while higher level of Hb at 3 months (p = 0.004) and formula feeding reduced the occurrence of ID/IDA at 6 months (p < 0.05); males had a 3.35 times higher risk to develop ID/IDA than girls (p = 0.021). No differences in growth and side effects were found. Conclusion: A daily dose of 2 mg/kg iron supplement is beneficial to maintain iron homeostasis in majority preterm infants within 6 months regardless of their neonatal anemia history. Under the routine iron supplementation, Hb level at birth and at 3 months, early treatment of blood transfusion, gender and feeding patterns are the major factors affecting the prevalence of ID/IDA among preterm infants in infancy.

Hepcidin, Serum Iron, and Transferrin Saturation in Full-Term and Premature Infants during the First Month of Life: A State-of-the-Art Review of Existing Evidence in Humans

Neonates regulate iron at birth and in early postnatal life. We reviewed literature from PubMed and Ovid Medline containing data on umbilical cord and venous blood concentrations of hepcidin and iron, and transferrin saturation (TSAT), in human neonates from 0 to 1 mo of age. Data from 59 studies were used to create reference ranges for hepcidin, iron, and TSAT for full-term-birth (FTB) neonates over the first month of life. In FTB neonates, venous hepcidin increases 100% over the first month of life (to reach 61.1 ng/mL; 95% CI: 20.1, 102.0 ng/mL) compared with umbilical cord blood (29.7 ng/mL; 95% CI: 21.1, 38.3 ng/mL). Cord blood has a high concentration of serum iron (28.4 μmol/L; 95% CI: 26.0, 31.1 μmol/L) and levels of TSAT (51.7%; 95% CI: 46.5%, 56.9%). After a short-lived immediate postnatal hypoferremia, iron and TSAT rebounded to approximately half the levels in the cord by the end of the first month. There were insufficient data to formulate reference ranges for preterm neonates.

The Role of Iron in Brain Development: A Systematic Review

One-third of children falter in cognitive development by pre-school age. Iron plays an important role in many neurodevelopmental processes, and animal studies suggest that iron sufficiency in pregnancy and infancy is particularly important for neurodevelopment. However, it is not clear whether iron deficiency directly impacts developmental outcomes, and, if so, whether impact differs by timing of exposure or developmental domain. We searched four databases for studies on iron deficiency or iron supplementation in pregnancy, or at 0-6 months, 6-24 months, or 2-4 years of age. All studies included neurodevelopmental assessments in infants or children up to 4 years old. We then qualitatively synthesized the literature. There was no clear relationship between iron status and developmental outcomes across any of the time windows or domains included. We identified a large quantity of low-quality studies, significant heterogeneity in study design and a lack of research focused on pregnancy and early infancy. In summary, despite good mechanistic evidence for the role of iron in brain development, evidence for the impact of iron deficiency or iron supplementation on early development is inconsistent. Further high-quality research is needed, particularly within pregnancy and early infancy, which has previously been neglected.

Association of maternal hemoglobin and iron stores with neonatal hemoglobin and iron stores

Background

One of the commonest causes of anemia in pregnancy is iron deficiency. This study aims at understanding and exploring the association between fetal and maternal iron status. Predelivery maternal hemoglobin (Hb) and iron stores, serum iron, ferritin, and soluble transferrin receptor (sTfR), were assessed and compared to the cord blood Hb and iron stores with an attempt to identify the level of maternal Hb and ferritin at which the fetal iron stores reduce, helping to identify the neonates who will require earlier iron supplementation.

Method

Four hundred eight participants were enrolled, and maternal and cord blood was collected at the time of delivery and tested for Hb and iron parameters. The results were statistically analyzed.

Results

Of all mothers, 27.2% mothers were anemic (Hb less than 11 g/dl). Of all newborns, 15.4% newborns had Hb less than 14 g/dl. There was a significant association between the maternal and cord blood iron, ferritin, sTfR and sTfR/log ferritin index. Eighty-five percent of the babies with cord blood Hb <14 g/dl had maternal serum ferritin (SF) <50 μg/L. Maternal SF <10 μg/l was associated with a significant number of babies with cord blood SF <75 μg/l (77.7%). One hundred sixty six neonates had sTfR 2 μg/ml or more. Of these, 80.7% had maternal SF <50 μg/l. Of the 115 newborns with a high sTfR/log ferritin index (>1.5), 56.5% had raised maternal sTfR (>2μg/ml).

Conclusion

In view of a significant association between maternal and neonatal Hb and iron stores, newborns of mothers with iron deficiency anemia (IDA) during pregnancy should be monitored and followed up after birth for development of IDA and early iron supplementation.

Inadequate iron stores in early term neonates

OBJECTIVE

To characterize neonatal iron stores depending on gestational age (GA) at term.

STUDY DESIGN

Participants were 751 mother-newborn pairs from the placebo arm of a randomized clinical trial of prenatal iron-folate supplementation in China. We compared mean cord serum ferritin (SF) by weeks GA and, following the general linear model, assessed whether maternal iron deficiency (ID) influenced relations between GA and cord SF.

RESULTS

Controlling for covariates, cord SF increased between 37 and 41 weeks (ps < 0.05-0.01). Cord SF was lower in infants of ID vs. non-ID mothers (geometric mean 96.3 [95% CI: 91.3-101.6] µg/L vs. 115.9 [95% CI: 105.0-127.8] µg/L, effect size = 0.33 SD, p = 0.0012). There was no significant increase with GA among infants of ID mothers. For non-ID mothers, cord-blood SF increased sharply with GA until 38 5/7 weeks, after which it plateaued.

CONCLUSIONS

The findings emphasize that neonates at 37-38 weeks, although considered term, are not fully mature.

Iron deficiency anemia in infants and toddlers

Background

In Korea, the prevalence of anemia and iron deficiency anemia (IDA) among older infants and young children remains high. To detect IDA early and to reduce its adverse impact, we assessed the characteristics of infants and young children who had IDA or were at risk of developing IDA, or who exhibited characteristics associated with severe anemia.

Methods

Among the 1,782 IDA-affected children aged 6 months to 18 years who visited the hospital, we retrospectively analyzed the medical records and laboratory data of 1,330 IDA-affected children aged 6–23 months who were diagnosed between 1996 and 2013. We excluded patients with a C-reactive protein level ≥5 mg/dL.

Results

IDA was predominant in boys (2.14:1) during infancy and early childhood. The peak IDA incidence was noted among infants aged 9–12 months. Only 7% patients exhibited symptoms of IDA, while 23.6% patients with severe IDA demonstrated classic symptoms/signs of IDA. Low birth weight (LBW) infants with IDA demonstrated low adherence to iron supplementation. In a multivariate analysis, prolonged breastfeeding without iron fortification (odds ratio [OR] 5.70), and a LBW (OR 6.49) were identified as risk factors of severe anemia.

Conclusion

LBW infants need more attention in order to increase their adherence to iron supplementation. For the early detection of IDA, nutritional status of all infants, and iron batteries of high-risk infants (LBW infants, infants with prolonged breastfeeding, picky eaters, and/or infants with the presence of IDA symptoms) should be evaluated at their health screening visits.

Developmental plasticity of red blood cell homeostasis

Most human physiologic set points like body temperature are tightly regulated and show little variation between healthy individuals. Red blood cell (RBC) characteristics such as hematocrit and mean cell volume are stable within individuals but can vary by 20% from one healthy person to the next. The mechanisms for the majority of this inter-individual variation are unknown and do not appear to involve common genetic variation. Here, we show that environmental conditions present during development, namely in utero iron availability, can exert long-term influence on a set point related to the RBC life cycle. In a controlled study of rhesus monkeys and a retrospective study of humans, we use a mathematical model of in vivo RBC population dynamics to show that in utero iron deficiency is associated with a lowered threshold for RBC clearance and turnover. This in utero effect is plastic, persisting at least 2 years after birth and after the cessation of iron deficiency. Our study reports a rare instance of developmental plasticity in the human hematologic system and also shows how mathematical modeling can be used to identify cellular mechanisms involved in the adaptive control of homeostatic set points.

The influences of factors associated with decreased iron supply to the fetus during pregnancy on iron status in healthy children aged 0.5 to 3 years

OBJECTIVE

To investigate whether maternal anemia, pregnancy-induced diabetes, hypertension and smoking contributed to the recently found high prevalence of iron deficiency in a population of otherwise healthy children.

STUDY DESIGN

Iron status was assessed in 400 children aged 0.5 to 3 years. We obtained information on the mothers' laboratory results, the presence of diabetes and hypertension, smoking habits and use of medication while pregnant.

RESULT

We found no influence of maternal anemia, diabetes, hypertension or smoking during pregnancy on iron status in the children. Mean corpuscular volume (MCV) values of the children were positively correlated to maternal MCV values.

CONCLUSION

In this population, iron status in children is not affected by maternal anemia or maternal factors that are associated with a decreased iron transport during pregnancy. The correlation between MCV values in mothers and their children might be explained by genetic and/or shared environmental factors.

Iron, human growth, and the global epidemic of obesity

Iron is an essential nutrient utilized in almost every aspect of cell function and its availability has previously limited life. Those same properties which allow iron to function as a catalyst in the reactions of life also present a threat via generation of oxygen-based free radicals. Accordingly; life exists at the interface of iron-deficiency and iron-sufficiency. We propose that: (1) human life is no longer positioned at the limits of iron availability following several decades of fortification and supplementation and there is now an overabundance of the metal among individuals of many societies; (2) this increased iron availability exerts a positive effect on growth by targeting molecules critical in regulating the progression of the cell cycle; there is increased growth in humans provided greater amounts of this metal; and indices of obesity can positively correlate with body stores of iron; and (3) diseases of obesity reflect this over-abundance of iron. Testing potential associations between iron availability and both obesity and obesity-related diseases in populations will be difficult since fortification and supplementation is so extensively practiced.

Influence of iron status on risk of maternal or neonatal infection and on neonatal mortality with an emphasis on developing countries

Infection is a major cause of neonatal death in developing countries. This review investigates whether host iron status affects the risk of maternal and/or neonatal infection, potentially contributing to neonatal death, and summarizes the iron acquisition mechanisms described for pathogens causing stillbirth, preterm birth, and congenital infection. In vitro evidence shows that iron availability influences the severity and chronicity of infections that cause these negative outcomes of pregnancy. In vivo evidence is lacking, as relevant studies of maternal iron supplementation have not assessed the effect of iron status on the risk of maternal and/or neonatal infection. Reducing iron-deficiency anemia among women is beneficial and should improve the iron stores of babies; moreover, there is evidence that iron status in young children predicts the risk of malaria and, possibly, the risk of invasive bacterial diseases. Caution with maternal iron supplementation is indicated in iron-replete women who may be at high risk of exposure to infection, although distinguishing between iron-replete and iron-deficient women is currently difficult in developing countries, where a point-of-care test is needed. Further research is indicated to investigate the risk of infection relative to iron status in mothers and babies in order to avoid iron intervention strategies that may result in detrimental birth outcomes in some groups of women.

Sex and gestational age effects on auditory brainstem responses in preterm and term infants

BACKGROUND

Some studies find delayed development of the auditory brainstem in preterm infants, but others do not.

AIM

To compare auditory brainstem responses (ABRs) in healthy preterm and term infants depending on sex and gestational age (GA).

METHODS

Participants were 111 preterm (27-36weeks GA) and 92 term (37-41weeks GA) infants. ABR tests were conducted at 6weeks (corrected age if preterm).

RESULTS

There were no overall differences between term and preterm groups in ABRs. However, males showed longer latencies for waves III, V, and I-III, III-V, and I-V intervals and smaller amplitudes for wave III and V than females in both preterm and term groups (all p values≤.01). A 3-way interaction between group, sex, and GA (p<.05) showed that preterm males with later GA had longer wave I-V interval, whereas term females with later GA showed shorter wave I-V interval. Growth velocity predicted wave I-V interval in preterm infants, controlling for other factors (male: p=.07, female: p<.05).

CONCLUSION

ABRs in preterm and term infants were similar at 6weeks (corrected age if preterm), but males had less advanced ABRs than females. More rapid growth predicted less mature ABR in later GA preterm infants in this setting where they were unlikely to receive extra iron. The roles of GA, growth, and iron balance in ABR development warrant further study.

Iron status in pregnant women in the Republic of Seychelles

OBJECTIVE

To establish the Fe status of pregnant women and their neonates in the Republic of Seychelles.

DESIGN

A prospective study.

SETTING

Republic of Seychelles.

SUBJECTS

Pregnant women were recruited and blood samples taken at enrolment and post-delivery along with cord blood samples. Ferritin and soluble transferrin receptor (sTfR) were measured in maternal (n 220) and cord blood (n 123) samples.

RESULTS

Maternal Fe deficiency (ferritin < 15 ng/ml, sTfR > 28 nmol/l) was present in 6 % of subjects at enrolment and in 20 % at delivery. There was no significant decrease in maternal ferritin. A significant increase in sTfR was observed between enrolment and delivery (P < 0.001). Maternal BMI and use of Fe supplements at 28 weeks' gestation were associated with improved maternal Fe status at delivery, whereas parity had a negative effect on sTfR and ferritin at delivery.

CONCLUSIONS

Fe status of pregnant Seychellois women was, on average, within normal ranges. The incidence of Fe deficiency throughout pregnancy in this population was similar to that in a Westernised population. Increased awareness of the importance of adequate Fe intake during pregnancy, particularly in multiparous women, is warranted.

Maternal iron deficiency and the risk of schizophrenia in offspring

CONTEXT

Iron is essential for brain development and functioning. Emerging evidence suggests that iron deficiency in early life leads to long-lasting neural and behavioral deficits in infants and children. Adopting a life course perspective, we examined the effects of early iron deficiency on the risk of schizophrenia in adulthood.

OBJECTIVE

To determine whether maternal iron deficiency, assessed by maternal hemoglobin concentration during pregnancy, increases the susceptibility to schizophrenia spectrum disorders (SSDs) among offspring.

DESIGN

Data were drawn from a population-based cohort born from 1959 through 1967 and followed up for development of SSD from 1981 through 1997.

PARTICIPANTS

Of 6872 offspring for whom maternal hemoglobin concentration was available, 57 had SSDs (0.8%) and 6815 did not (99.2%).

MAIN OUTCOME MEASURE

Prospectively assayed, the mean value of maternal hemoglobin concentration was the primary exposure. Hemoglobin concentration was analyzed as a continuous and a categorical variable.

RESULTS

A mean maternal hemoglobin concentration of 10.0 g/dL or less was associated with a nearly 4-fold statistically significant increased rate of SSDs (adjusted rate ratio, 3.73; 95% confidence interval, 1.41-9.81; P = .008) compared with a mean maternal hemoglobin concentration of 12.0 g/dL or higher, adjusting for maternal education and ethnicity. For every 1-g/dL increase in mean maternal hemoglobin concentration, a 27% decrease in the rate of SSDs was observed (95% confidence interval, 0.55-0.96; P = .02).

CONCLUSIONS

The findings suggest that maternal iron deficiency may be a risk factor for SSDs among offspring. Given that this hypothesis offers the potential for reducing the risk for SSDs, further investigation in independent samples is warranted.

The relationship between red blood cell and reticulocyte indices and serum markers of iron status in the cord blood of newborns

BACKGROUND

The aims of this study were to assess the relationship between red blood cell and reticulocyte indices and biochemical iron status measurements, and to define reference values of these markers in the cord blood of newborns.

METHODS

In cord blood samples from 199 full-term newborns, cellular indices were assessed using an ADVIA 120 hematology system and iron status was analyzed by measurement of serum iron, transferrin, transferrin saturation (TfSat), transferrin receptor (TfR) and ferritin.

RESULTS

Cellular hemoglobin in red blood cells or reticulocytes was independent of serum iron markers such as TfSat, TfR and ferritin. The percentage of hypochromic red blood cells (%HYPOm) and reticulocytes (%HYPOr) correlated significantly with TfSat and TfR-F index (TfR/log ferritin). Importantly, %HYPOm and %HYPOr were also positively correlated with the high immature reticulocyte fraction (IRF-H) and the mean cell volume of red or reticulocytes.

CONCLUSIONS

In newborns, accelerated erythropoiesis is a major contributor to red blood cell and reticulocyte indices, which provide conflicting results when compared with serum markers of iron status. Apparently, the serum proteins ferritin, transferrin and TfR are more appropriate tools for the diagnosis of iron status in newborns.

Iron deficiency in infancy: applying a physiologic framework for prediction

BACKGROUND

Infants aged 6-24 mo are at high risk of iron deficiency. Numerous studies worldwide have sought to identify predictors of iron deficiency in this age group.

OBJECTIVE

The objectives of the study were to apply a physiologic model to identify risk factors for iron deficiency and to consider those risk factors under different conditions of iron supplementation. We predicted that factors related to iron status at birth (lower gestational age and lower birth weight), postnatal needs for iron (more rapid growth), and bioavailable iron (more cow milk) would be major risk factors.

DESIGN

The physiologic framework was assessed in 1657 Chilean infants (aged 12 mo) with birth weights >or=3 kg who were randomly assigned at age 6 mo to high or low iron supplementation or no added iron. Based on venous blood, the analysis used mean corpuscular volume and concentrations of hemoglobin, free erythrocyte protoporphyrin, and ferritin. Logistic regression models were used to identify predictors of iron deficiency anemia and iron deficiency without anemia.

RESULTS

The prevalence of iron deficiency (>or=2 abnormal iron measures) was 34.9% at age 12 mo. Of 186 infants with hemoglobin concentrations <110 g/L, 158 (84.9%) were iron deficient. The only consistent (and the strongest) predictor of iron deficiency or iron deficiency anemia was lower 6-mo hemoglobin. Factors related to poorer iron status at birth (lower birth weight, shorter gestation though full-term, or both) were predictors in the no-added-iron and high-iron groups. Otherwise, predictors varied by iron supplementation.

CONCLUSION

Variations in predictors of iron deficiency or iron deficiency anemia according to iron supplementation suggest that direct comparisons across studies are tenuous at best without data on early iron status and certainty that specific conditions are comparable.

Impact of maternal anemia on the infant's iron status at 9 months of age

BACKGROUND

Iron-deficiency anemia during pregnancy is still common in developed countries. The aim of this study was to evaluate the influence of maternal anemia on the infant's iron status at 9 months of age in Moncton, NB.

METHODS

Mothers giving birth between April 1998 and February 1999 were selected from medical records. A letter was sent to invite them to participate. In total, 75 mothers with their infants were examined.

RESULTS

The proportion of iron-deficiency anemia was higher (p = 0.055) in the group born to anemic compared to non-anemic mothers. A positive association between the mother's haemoglobin and haematocrit during her 3rd trimester and her infant's haemoglobin and haematocrit was found at 9 months of age. These results are not explained by differences in feeding practices and socio-economic status between groups.

INTERPRETATION

Infants born to mildly anemic mothers may be at risk of developing anemia.