Maternal and Cord Blood Hepcidin Concentrations in Severe Iron Deficiency Anemia

The association between maternal anemia and neonatal anemia: a systematic review and meta-analysis

IMPORTANCE

Neonatal anemia has a long-term effect on children's growth and development. Anemia during pregnancy is also the most widespread nutritional deficiency among pregnant women in the world; If it leads to anemia in newborns, it will affect a wide range of people and be a public health problem worthy of attention.

OBJECTIVE

To study the relationship between maternal anemia during pregnancy and neonatal hemoglobin levels.

DATA SOURCES

PubMed, Web of science, Scopus, MEDLINE, Embase, ProQuest, Dissertations & Theses Global, The Cochrane Library, China Biology Medicine Database, Chinese CNKI Database, and Chinese Wanfang Database were systematically searched from inception to August 31, 2022.

STUDY SELECTION

The meta-analysis included all original studies which pertain to   cohort studies, case-control studies or cross-sectional studies that investigated the relationship between maternal anemia during pregnancy and neonatal hemoglobin levels.

DATA EXTRACTION AND SYNTHESIS

Hemoglobin level of both anemic and non-anemic  pregnant mothers and their paired newborns were pooled from the selected studies. The random-effects model was used to assess the risk of getting a lower neonatal hemoglobin level between mothers with and without pregnant anemia. Data analyses were performed from September 5, 2022, to March 10, 2023.

MAIN OUTCOMES AND MEASURES

Maternal anemia during pregnancy is a risk factor of lower neonatal hemoglobin levels.

RESULTS

The initial search yielded 4267 records of which 116 articles underwent full-text evaluation, which identified 18 articles and a total of 1873 patients that were included. The findings of the meta-analysis showed a significant difference between the two groups(MD=-1.38; 95%CI:[-1.96,-0.80]. p<0.01), while the co-effect showed that the neonatal hemoglobin value of anemic mothers was 1.38g/dL lower than that of non-anemic mothers(-1.96,-0.80), suggesting a correlation between maternal anemia lower neonatal hemoglobin levels.

CONCLUSIONS AND RELEVANCE

This systematic review and meta-analysis demonstrated that maternal anemia during pregnancy were associated with a lower level of newborn hemoglobin levels. This may enable a better understanding of neonatal anemia and provide guidance towards future development of nutritional supplementation during pregnancy and the prediction of postpartum outcomes.

TRIAL REGISTRATION

PROSPERO Identifier: CRD42022352759.

Biomarkers of Brain Dysfunction in Perinatal Iron Deficiency

Iron deficiency in the fetal and neonatal period (perinatal iron deficiency) bodes poorly for neurodevelopment. Given its common occurrence and the negative impact on brain development, a screening and treatment strategy that is focused on optimizing brain development in perinatal iron deficiency is necessary. Pediatric societies currently recommend a universal iron supplementation strategy for full-term and preterm infants that does not consider individual variation in body iron status and thus could lead to undertreatment or overtreatment. Moreover, the focus is on hematological normalcy and not optimal brain development. Several serum iron indices and hematological parameters in the perinatal period are associated with a risk of abnormal neurodevelopment, suggesting their potential use as biomarkers for screening and monitoring treatment in infants at risk for perinatal iron deficiency. A biomarker-based screening and treatment strategy that is focused on optimizing brain development will likely improve outcomes in perinatal iron deficiency.

Molecular insights into placental iron transfer mechanisms and maternofetal regulation

PURPOSE

Adequate iron transportation from the mother across the placenta is crucial for fetal growth and establishing sufficient iron stores in neonates at birth. The past decade has marked significant discoveries in iron metabolism with the identification of new players and mechanisms. Immunohistochemical studies rendered valuable data on the localization of substantial iron transporters on placental syncytiotrophoblasts. However, the function and regulation of maternal-placentofetal iron transporters and iron handling is still elusive and requires more attention.

METHODS

A thorough literature review was conducted to gather information about placental iron transfer, the role of regulators and maintenance of iron homeostasis.

RESULTS

The role of classical and new players in maternal-fetal iron transport and the regulation in the placenta has been addressed in this review. Animal and human studies have been discussed. The role of placental iron regulation in thalassemia and hemochromatosis pregnancies has been reviewed.

CONCLUSIONS

The current advances that highlight the mechanisms of placental iron regulation and transport in response to maternal and fetal signals have been presented.

Elevated first-trimester hepcidin level is associated with reduced risk of iron deficiency anemia in late pregnancy: a prospective cohort study

Background

Iron deficiency (ID) and iron deficiency anemia (IDA) during pregnancy are highly prevalent worldwide. Hepcidin is considered an important biomarker of iron status. Currently, few longitudinal cohort studies have assessed the potential causal relationship between hepcidin and ID/IDA. Therefore, we aimed to investigate the association of first-trimester maternal serum hepcidin with third-trimester ID/IDA risk in a prospective cohort.

Methods

Total of 353 non-ID/IDA pregnant women at 11-13 weeks' gestation were enrolled in Southern China and followed up to 38 weeks of gestation. Data on demography and anthropometry were obtained from a structured questionnaire at enrollment. Iron biomarkers including hepcidin were measured at enrollment and follow-up. Regression models were used to evaluate the association of first-trimester hepcidin with third-trimester ID/IDA risk.

Results

Serum hepcidin levels substantially decreased from 19.39 ng/mL in the first trimester to 1.32 ng/mL in the third trimester. Incidences of third-trimester ID and IDA were 46.2 and 11.4%, respectively. Moreover, moderate and high levels of first-trimester hepcidin were positively related to third-trimester hepcidin (log-transformed β = 0.51; 95% CI = 0.01, 1.00 and log-transformed β = 0.66; 95% CI = 0.15, 1.17). Importantly, elevated first-trimester hepcidin was significantly associated with reduced risk of third-trimester IDA (OR = 0.38; 95% CI = 0.15, 0.99), but not with ID after adjustment with potential confounders.

Conclusion

First-trimester hepcidin was negatively associated with IDA risk in late pregnancy, indicating higher first-trimester hepcidin level may predict reduced risk for developing IDA. Nonetheless, given the limited sample size, larger studies are still needed.

Hepcidin across pregnancy and its correlation with maternal markers of iron and inflammation, maternal body weight outcomes, and offspring neurodevelopmental outcomes: a systematic review and meta-analysis

OBJECTIVE

This study evaluated the correlation between maternal hepcidin and other biomarkers of iron status, markers of inflammation, and maternal body weight during pregnancy, as well as neurodevelopment in the offspring.

DATA SOURCES

PubMed, Web of Science, Scopus, and Embase were searched from inception until March 2022.

STUDY ELIGIBILITY CRITERIA

Studies conducted among pregnant women without apparent pregnancy complications were included. Eligible studies reported correlation coefficients between maternal hepcidin and any outcomes of maternal biomarkers of iron status or inflammatory load during pregnancy, prenatal maternal body weight, and offspring neurodevelopment. Studies without correlation data were eligible if they quantitatively reported volumes of both maternal hepcidin and any marker of iron status and/or inflammatory load during gestation.

METHODS

Pooled correlation coefficients between maternal hepcidin and outcomes of interest were calculated using the Fisher r-to-Z transformation. Both fixed-effects and DerSimonian and Laird random-effects models were used to calculate pooled correlation coefficient. When meta-analysis was not feasible, results were descriptively synthesized.

RESULTS

Forty-six studies with 6624 participants were eligible. Hepcidin was significantly correlated with hemoglobin in the third trimester (r=0.21; 95% confidence interval, 0.1-0.32); ferritin in the first (r=0.31; 95% confidence interval, 0.01-0.61) and third trimester (r=0.35; 95% confidence interval, 0.23-0.48); soluble transferrin receptor in the second trimester (r=-0.27; 95% confidence interval, -0.4 to -0.14); total iron-binding capacity in the second trimester (r=0.37; 95% confidence interval, 0.24-0.50); and serum iron in the third trimester (r=0.11; 95% confidence interval, 0.02-0.19). Hepcidin was significantly correlated with the inflammatory marker interleukin-6 in the third trimester (r=0.26; 95% confidence interval, 0.17-0.34) and C-reactive protein in the second (r=0.16; 95% confidence interval, 0.03-0.30) and third trimester (r=0.28; 95% confidence interval, 0.04-0.52). Four out of 5 studies reported weak-to-moderate positive correlation between hepcidin and body mass index. Hepcidin levels varied across body mass index categories. No single study reported the relationship between maternal hepcidin and neurodevelopment in offspring.

CONCLUSION

Hepcidin weakly to moderately correlates with biomarkers of iron and inflammation in pregnancy.

Adaptive response of estrogen-iron axis in pregnant Purebred Spanish mares of different age

The maintenance of iron (Fe) homeostasis is vital for the physiological function along life. In sexually mature humans and experimental animals, estrogens downregulate hepcidin (Hpc) expression, in order to improve the intestinal absorption and to mobilize Fe stores for maternal erythropoietic expansion and placental development. However, changes of these mechanisms related to regulation of Hpc on the availability of Fe during gestation with advancing age in mares, remain unknown. The objective of this study was to evaluate the interrelationships between serum Fe, Ferritin (Ferr) and Hpc with estrone (E₁) and estradiol-17β (E₂) concentrations in pregnant mares of different ages. Blood samples were taken from 40 pregnant Spanish Purebred mares belonging to 4 different age groups, 10 subjects for each group: 4-6 years, 7-9 years, 10-12 years, and > 12 years were used in this study. Fe concentrations of 4-6 and 7-9 years groups were higher (P < .01) than 10-12 and >12 years groups. Ferr concentrations of 4-6 years group were higher (P < .01) than other groups. Hpc concentrations increased and E₁ decreased (P < .01) in > 12 years group compared to other age groups. E₂ concentrations of 7-9, 10-12 and >12 years groups were higher (P < .01) than those of 4-6 years group; 7-9 years group had higher E₂ concentrations (P < .01) than > 12 years group. Fe and Ferr were negatively correlated with Hpc (r = -0.81 and r = -0.67, respectively). E₁ and E₂ were negatively correlated with Fe (r = -0.23 and r = -0.11, respectively). E₂ was positively correlated with Hpc (r = 0.78). In pregnant Spanish Purebred mare, the increase of estrogens, according to the more efficient iron status in response to Hpc inhibition and consequent mobilization of circulating and iron reserve, shows the existence of "estrogen-iron axis" in young mares. Nevertheless, these mechanisms are reversed in old mares, suggesting a less efficient iron metabolism with advancing age. It is hoped that new investigations are needed to understand in depth and clarify further the complex metabolic and hormonal mechanisms involved also in equine species.

Hepcidin, ferritin and iron homeostasis in pregnant Spanish Purebred mares

During pregnancy, maternal erythropoietic expansion and fetal development require greater mobilization of available iron (Fe) stores. These adjustments in Fe metabolism in humans and rodents are largely mediated by the hormone hepcidin (Hepc), which controls the expression of ferroportin (Fpn), a transporter responsible for exporting Fe from stores to extracellular fluid and plasma. These mechanisms based on the regulation of Hepc on the availability of Fe during gestation in healthy mares remain unknown. The objective of this study was to determine the existence of interrelationships among concentrations of Hepc, ferritin (Ferr), Fe, and estrone (E₁) and progesterone (P₄) in Spanish Purebred mares along the whole gestation. Blood samples were taken from 31 Spanish Purebred mares each month, during 11 months of pregnancy. Fe and Ferr significantly increased and Hepc decreased during pregnancy (P < 0.05). The secretion peak of estrone (E₁) was reached in the 5th month and progesterone (P₄) between the 2nd and 3rd months of gestation (P < 0.05). Fe and Ferr were weakly positively correlated (r = 0.57; P < 0.05). Fe and Ferr were negatively correlated with Hepc (r = -0.80 and r = -0.67, respectively) (P < 0.05). P₄ was positively correlated with Hepc (r = 0.53; P < 0.05). Pregnancy in the Spanish Purebred mare was characterized by a progressive increase in Fe and Ferr and a reduction in Hepc concentrations. E₁ was partially responsible for the suppression of Hepc; on the other hand, P₄ induced its stimulation during pregnancy in the mare.

The interplay between maternal-infant anemia and iron deficiency

Iron deficiency anemia in pregnancy is a major public health problem known to cause maternal morbidity and adverse birth outcomes, and it may also have lasting consequences on infant development. However, the impact of the maternal hematological environment on fetal and infant hemoglobin and iron stores in the first year of life remains unclear. This review of the epidemiological evidence found that severe maternal iron deficiency anemia in pregnancy is associated with lower ferritin, and to a lesser degree hemoglobin levels, in infants at birth. Emerging data also suggests that severe anemia in pregnancy increases the risk of iron deficiency and anemia in infants 6-12 months of age, although longitudinal studies are limited. Effective anemia prevention in pregnancy, such as iron supplementation, could reduce the risk of infant anemia and iron deficiency during the first year of life; however, more evidence is needed to determine the functional impact of iron supplementation in pregnancy on infant hematological indices.

Disordered Maternal and Fetal Iron Metabolism Occurs in Preterm Births in Human

Background. Increasing evidence reveals that iron deficiency during pregnancy causes adverse pregnancy outcomes. Thus far, the mechanisms underlying iron deficiency-associated preterm birth are mostly limited to animal studies. Whether the suggested mechanisms exist in human requires further investigation. The goal of this study was to characterize the iron metabolism in both the maternal side and fetal side in pregnant women with preterm birth. Methods. Serum and placenta samples were collected from 42 pregnant women divided into four groups according to the gestational week. Indicators of iron metabolism, including serum iron, serum hepcidin, placental tissue iron, ferroportin (FPN), transferrin receptor 1 (TfR1), and ferritin, were surveyed using enzyme-linked immunosorbent assays (Elisa), Western blots, and real-time quantitative polymerase chain reactions (qRT-PCR). Results. Significant reduction of maternal serum iron was observed in women with preterm birth relative to those with full-term birth, indicative of worsen iron deficiency in those mothers with preterm birth. Meanwhile, the maternal hepcidin levels were notably diminished in women with preterm birth, whereas the fetal hepcidin levels were comparable between the two groups. Moreover, the placental iron stores were remarkably reduced in the preterm group, associated with reduced concentration of TfR1 and increased FPN concentration relative to the normal controls. In other words, the ratio of placental FPN mass to TfR1 mass (PIDI index) was strikingly increased in the preterm group. Conclusions. Dysregulated iron homeostasis in both the maternal and fetal sides was implicated in preterm births, and disordered regulations in maintaining the placental iron equilibrium were also presumed to account for the compromised fetal iron supply.

Postdischarge Iron Status in Very Preterm Infants Receiving Prophylactic Iron Supplementation after Birth

OBJECTIVE

To determine postdischarge iron status and associated factors in very preterm infants.

STUDY DESIGN

A retrospective cohort study was conducted through a provincial database on all very preterm infants born in Nova Scotia between 2005 and 2018. As a standard of care, all infants received prophylactic iron supplements starting at 2-4 weeks of chronological age and were tested for iron deficiency at 4 or 6 months corrected age. Iron deficiency was defined as serum ferritin <20 g/L at 4 months or <12 g/L at 6 months. Multivariate logistic regression analysis identified factors associated with iron deficiency.

RESULTS

Among 411 infants, 132 (32.1%) had iron deficiency and 11 (2.7%) had iron deficiency anemia. The prevalence of iron deficiency decreased over time, from 37.6% in 2005-2011 to 25.8% in 2012-2018. Gestational hypertension in the mother (P = .01) and gestational age <27 weeks (P = .02) were independent risk factors for iron deficiency. In addition, the odds of iron deficiency were lower in the mixed-fed group (ie, with breast milk and formula combined) compared with the exclusive formula-fed group (P = .01).

CONCLUSIONS

Iron deficiency was prevalent in 32% of the very preterm infants despite early iron prophylaxis. These results demonstrate the importance of monitoring iron stores during preterm follow-up. Information about risk factors is important to mitigate iron deficiency in very preterm infants.

Iron deficiency during the first 1000 days of life: are we doing enough to protect the developing brain?

Iron is essential for the functioning of all cells and organs, most critically for the developing brain in the fundamental neuronal processes of myelination, energy and neurotransmitter metabolism. Iron deficiency, especially in the first 1000 days of life, can result in long-lasting, irreversible deficits in cognition, motor function and behaviour. Pregnant women, infants and young children are most vulnerable to iron deficiency, due to their high requirements to support growth and development, coupled with a frequently inadequate dietary supply. An unrecognised problem is that even if iron intake is adequate, common pregnancy-related and lifestyle factors can affect maternal-fetal iron supply in utero, resulting in an increased risk of deficiency for the mother and her fetus. Although preterm birth, gestational diabetes mellitus and intrauterine growth restriction are known risk factors, more recent evidence suggests that maternal obesity and delivery by caesarean section further increase the risk of iron deficiency in the newborn infant, which can persist into early childhood. Despite the considerable threat that early-life iron deficiency poses to long-term neurological development, life chances and a country's overall social and economic progress, strategies to tackle the issue are non-existent, too limited or totally inappropriate. Prevention strategies, focused on improving the health and nutritional status of women of reproductive age are required. Delayed cord clamping should be considered a priority. Better screening strategies to enable the early detection of iron deficiency during pregnancy and early-life should be prioritised, with intervention strategies to protect maternal health and the developing brain.

Umbilical Cord Erythroferrone Is Inversely Associated with Hepcidin, but Does Not Capture the Most Variability in Iron Status of Neonates Born to Teens Carrying Singletons and Women Carrying Multiples

BACKGROUND

The developing fetus requires adequate iron and produces its own hormones to regulate this process. Erythroferrone (ERFE) is a recently identified iron regulatory hormone, and normative data on ERFE concentrations and relations between iron status and other iron regulatory hormones at birth are needed.

OBJECTIVES

The objective of this study was to characterize cord ERFE concentrations at birth and assess interrelations between ERFE, iron regulatory hormones, and iron status biomarkers in 2 cohorts of newborns at higher risk of neonatal anemia.

METHODS

Umbilical cord ERFE concentrations were measured in extant serum samples collected from neonates born to women carrying multiples (age: 21-43 y; n = 127) or teens (age: 14-19 y; n = 164). Relations between cord blood ERFE and other markers of iron status or erythropoiesis in cord blood were assessed by linear regression and mediation analysis.

RESULTS

Cord ERFE was detectable in all newborns delivered between 30 and 42 weeks of gestation, and mean concentration at birth was 0.73 ng/mL (95% CI: 0.63, 0.85 ng/mL). Cord ERFE was on average 0.25 ng/mL lower in newborns of black as opposed to white ancestry (P = 0.04). Cord ERFE was significantly associated with transferrin receptor (β: 1.17, P < 0.001), ferritin (β: -0.27, P < 0.01), and hemoglobin (Hb) (β: 0.04, P < 0.05). However, cord hepcidin and the hepcidin:erythropoietin (EPO) ratio captured the most variance in newborn iron and hematologic status (>25% of variance explained).

CONCLUSIONS

Neonates born to teens and women carrying multiples were able to produce ERFE in response to neonatal cord iron status and erythropoietic demand. ERFE, however, did not capture significant variance in newborn iron or Hb concentrations. In these newborns, cord hepcidin and the hepcidin:EPO ratio explained the most variance in iron status indicators at birth.

Iron stores at birth in a full-term normal birth weight birth cohort with a low level of inflammation

Iron stores at birth are essential to meet iron needs during the first 4-6 months of life. The present study aimed to investigate iron stores in normal birth weight, healthy, term neonates. Umbilical cord blood samples were collected from apparently normal singleton vaginal deliveries (n=854). Subjects were screened and excluded if C-reactive protein (CRP) > 5 mg/l or α1-acid glycoprotein (AGP) > 1 g/l, preterm (<37 complete weeks), term < 2500g or term > 4000g. In total, 762 samples were included in the study. Serum ferritin, soluble transferrin receptor (sTfR), hepcidin, and erythropoietin (EPO) were measured in umbilical cord blood samples; total body iron (TBI) (mg/kg) was calculated using sTfR and ferritin concentrations. A total of 19.8% newborns were iron deficient (ferritin 35 μg/l) and an additional 46.6% had insufficient iron stores (ferritin < 76 μg/l). There was a positive association between serum ferritin and sTfR, hepcidin, and EPO. Gestational age was positively associated with ferritin, sTfR, EPO, and hepcidin. In conclusion, we demonstrate a high prevalence of insufficient iron stores in a Chinese birth cohort. The value of cord sTfR and TBI in the assessment of iron status in the newborn is questionable, and reference ranges need to be established.

Maternal and Cord Blood Hemoglobin as Determinants of Placental Weight: A Cross-Sectional Study

Background: Both high and low placental weights are associated with adverse pregnancy outcomes. Maternal hemoglobin levels can influence placental weight, but the evidence is conflicting. Since maternal hemoglobin does not invariably correlate with fetal/neonatal blood hemoglobin levels, we sought to determine whether cord blood hemoglobin or maternal hemoglobin status more closely associates with placental weight in women undergoing elective cesarean section at term. Methods: This was a cross-sectional study conducted at the Royal Alexandra Hospital, Edmonton, Canada, involving 202 women with term singleton pregnancies undergoing elective cesarean section. Maternal blood and mixed cord blood hemoglobin levels were analyzed using a HemoCue Hb201+ system. Birth weight, placental weight, one- and five-minute APGAR scores, American Society of Anesthesiologists physical state classification, maternal age, and maternal height were also recorded. Relationships between maternal and cord blood hemoglobin levels with placental weight, birth weight, and birth weight to placental weight ratio were the main outcome measures. Results: A total of 182 subjects were included in the analysis. Regression analysis showed that cord blood hemoglobin, but not maternal hemoglobin, was inversely related with placental weight (β = −2.4, p = 0.001) and positively related with the birth weight to placental weight ratio (β = 0.015, p = 0.001 and p = 0.63, respectively). Conclusions: Our findings suggest that measuring cord blood hemoglobin levels, rather than maternal hemoglobin levels, may provide important diagnostic information about in utero fetal adaptation to suboptimal placental function and neonatal health.

Neonatal Levels of Acute Phase Proteins and Risk of Autism Spectrum Disorder

BACKGROUND

Immune signaling pathways influence neurodevelopment and are hypothesized to contribute to the etiology of autism spectrum disorder (ASD). We aimed to assess risk of ASD in relation to levels of neonatal acute phase proteins (APPs), key components of innate immune function, measured in neonatal dried blood spots.

METHODS

We included 924 ASD cases, 1092 unaffected population-based controls, and 203 unaffected siblings of ASD cases in this case-control study nested within the register-based Stockholm Youth Cohort. Concentrations of 9 different APPs were measured in eluates from neonatal dried blood spots from cases, controls, and siblings using a bead-based multiplex assay.

RESULTS

Neonatal C-reactive protein was consistently associated with odds of ASD in case-control comparisons, with higher odds associated with the highest quintile compared with the middle quintile (odds ratio [OR] = 1.50, 95% confidence interval [CI] = 1.10-2.04) in adjusted analyses. In contrast, the lowest quintiles of α-2-macroglobulin (OR = 3.71, CI = 1.21-11.33), ferritin (OR = 4.20, CI = 1.40-12.65), and serum amyloid P (OR = 3.05, CI = 1.16-8.01) were associated with odds of ASD in the matched sibling comparison. Neonatal APPs varied with perinatal environmental factors and maternal/fetal phenotypes. Significant interactions in terms of risk for ASD were observed between neonatal APPs and maternal infection during late pregnancy, maternal anemia, and maternal psychiatric history.

CONCLUSIONS

Indicators of the neonatal innate immune response are associated with risk of ASD, although the nature of these associations varies considerably with factors in the perinatal environment and the genetic background of the comparison group.

A systematic review and meta-analysis of the correlation between maternal and neonatal iron status and haematologic indices

BACKGROUND

Iron deficiency (ID) is the leading single-nutrient deficiency in the world. Anaemia is a common outcome of ID that affects half of pregnancies worldwide with serious consequences for child development. Whether haematologic indices and biomarkers of iron status in pregnant women correlate with those of their neonates is unclear. This systematic review evaluated studies comparing haematologic and iron status indices in pregnant women and their newborns/neonates.

METHODS

We searched MEDLINE, EMBASE, CINAHL, and Web of Science from database inception until March 2020 for primary studies comparing haematologic and iron status indices between women and their newborns up to 48 h after birth. We summarized the results descriptively and calculated pooled correlation coefficients in mothers and newborns/neonates using the Schmidt-Hunter method. The protocol was registered at PROSPERO International Prospective Register of Systematic Reviews (Registration number: CRD42018093094).

FINDINGS

Sixty-five studies were included. Pooled correlation coefficients for biomarkers of iron status in mothers and newborns/neonates were 0.13 (ferritin), 0.42 (hepcidin), 0.30 (serum/plasma iron), 0.09 (transferrin), 0.20 (transferrin saturation), and 0.16 (total iron binding capacity). Pooled correlation coefficients for haematological indices in mothers and newborns/neonates were 0.15 (haemoglobin), 0.15 (haematocrit), 0.25 (mean cell/corpuscular haemoglobin), 0.22 (mean cell/corpuscular volume).

INTERPRETATION

Maternal biomarkers of iron and haematologic status correlate poorly with those in newborns/neonates. These results underscore a need for alternative approaches to estimate foetal/neonatal iron status and haematological indices.

FUNDING

MBO and SLB hold Canada Research Chairs, and grants from the Women and Children's Health Research Institute and Canadian Institutes of Health Research.

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.

Hepcidin mediates hypoferremia and reduces the growth potential of bacteria in the immediate post-natal period in human neonates

Septicemia is a leading cause of death among neonates in low-income settings, a situation that is deteriorating due to high levels of antimicrobial resistance. Novel interventions are urgently needed. Iron stimulates the growth of most bacteria and hypoferremia induced by the acute phase response is a key element of innate immunity. Cord blood, which has high levels of hemoglobin, iron and transferrin saturation, has hitherto been used as a proxy for the iron status of neonates. We investigated hepcidin-mediated redistribution of iron in the immediate post-natal period and tested the effect of the observed hypoferremia on the growth of pathogens frequently associated with neonatal sepsis. Healthy, vaginally delivered neonates were enrolled in a cohort study at a single center in rural Gambia (N = 120). Cord blood and two further blood samples up to 96 hours of age were analyzed for markers of iron metabolism. Samples pooled by transferrin saturation were used to conduct ex-vivo growth assays with Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli and Klebsiella pneumonia. A profound reduction in transferrin saturation occurred within the first 12 h of life, from high mean levels in cord blood (47.6% (95% CI 43.7–51.5%)) to levels at the lower end of the normal reference range by 24 h of age (24.4% (21.2–27.6%)). These levels remained suppressed to 48 h of age with some recovery by 96 h. Reductions in serum iron were associated with high hepcidin and IL-6 levels. Ex-vivo growth of all sentinel pathogens was strongly associated with serum transferrin saturation. These results suggest the possibility that the hypoferremia could be augmented (e.g. by mini-hepcidins) as a novel therapeutic option that would not be vulnerable to antimicrobial resistance. Trial registration: The original trial in which this study was nested is registered at ISRCTN, number 93854442.

Active Tobacco Smoke Exposure in Utero and Concentrations of Hepcidin and Selected Iron Parameters in Newborns

The aim of this study was to assess the influence of active tobacco smoke exposure in utero on the concentration of hepcidin and selected iron markers in umbilical cord blood and to evaluate the relationships between these parameters. Newborns of smoking mothers had significantly lower concentrations of serum hepcidin (p < 0.001), iron, and ferritin (p = 0.043; p = 0.042, respectively), but higher levels of erythropoietin (EPO, p < 0.001) and soluble transferrin receptor (sTfR, p = 0.011) compared with newborns of non-smoking women. Negative correlations between cotinine and the number of cigarettes smoked per day with hepcidin serum level (r = −0.33, p = 0.033, r = −0.32, p = 0.041, respectively) and EPO (r = 0.47, p = 0.002; r = 0.46, p = 0.003, respectively) were found. Univariate analysis defined for the whole group of children revealed significant associations between the concentration of hepcidin and other iron status parameters. In the models estimated separately for smokers and non-smokers, we found relations between the level of hepcidin and erythropoietin (B = −0.23, p = 0.004; B = −0.46, p = 0.01, respectively). In the multivariate regression model, a negative association between hepcidin and EPO concentrations in the whole group of newborns (β = −0.53; p = 0.001) and in the group of smokers (β = −0.57; p = 0.011) was confirmed. The present study shows significant relations between smoking during pregnancy and hepcidin levels in children born at term. Decreased cord serum concentrations of hepcidin associated with high erythropoietin levels suggest induced fetal erythropoiesis, probably due to the hypoxic effects imposed by maternal smoking.

Umbilical Cord Serum Ferritin Concentration is Inversely Associated with Umbilical Cord Hemoglobin in Neonates Born to Adolescents Carrying Singletons and Women Carrying Multiples

BACKGROUND

It has been proposed that the fetus prioritizes iron for hemoglobin production over delivery to tissues. However, few studies have evaluated the interrelations between hemoglobin and multiple iron status biomarkers in umbilical cord blood. A full understanding is needed of how these parameters influence each other within cord blood to fully interpret iron and hematologic status at birth.

OBJECTIVES

We evaluated the determinants of neonatal hemoglobin and assessed the interrelations between hemoglobin, serum iron status indicators, and serum iron regulatory hormones in healthy neonates.

METHODS

This was an observational study that assessed umbilical cord hemoglobin (Hb), serum ferritin (SF), erythropoietin (EPO), soluble transferrin receptor (sTfR), serum iron, hepcidin, vitamin B-12, folate, IL-6, and CRP measured in 234 neonates born to adolescents or to women carrying multiples. Correlations between these indicators were evaluated and mediation models consistent with the observed significant determinants of cord Hb concentrations were developed.

RESULTS

A highly significant inverse association was found between cord SF and Hb concentrations that was not attributable to neonatal or maternal inflammation (as measured by IL-6 and CRP). The inverse association was present in the combined cohort, as well as in the adolescent and multiples cohorts independently. Mediation analyses found that EPO and hepcidin had significant indirect effects on cord Hb, associations that are explicable by mediation through SF and sTfR.

CONCLUSION

In contrast to observations made in older infants, a highly significant inverse association between Hb and SF, as well positive associations between Hb and both sTfR and EPO, were observed in umbilical cord blood from neonates born to adolescents or women carrying multiples. These findings, combined with review of the published literature, indicate a need for analysis of the relations between multiple parameters to assess iron and hematologic status at birth. These clinical trials were registered at clinicaltrials.gov as NCT01582802 (https://clinicaltrials.gov/ct2/show/NCT01582802) and NCT01019902 (https://clinicaltrials.gov/ct2/show/NCT01019902).

Cord Blood Hepcidin: Cross-Sectional Correlates and Associations with Anemia, Malaria, and Mortality in a Tanzanian Birth Cohort Study

Hepcidin, the master regulator of bioavailable iron, is a key mediator of anemia and also plays a central role in host defense against infection. We hypothesized that measuring hepcidin levels in cord blood could provide an early indication of interindividual differences in iron regulation with quantifiable implications for anemia, malaria, and mortality-related risk. Hepcidin concentrations were measured in cord plasma from a birth cohort (N = 710), which was followed for up to 4 years in a region of perennial malaria transmission in Muheza, Tanzania (2002-2006). At the time of delivery, cord hepcidin levels were correlated with inflammatory mediators, iron markers, and maternal health conditions. Hepcidin levels were 30% (95% confidence interval [CI]: 12%, 44%) lower in children born to anemic mothers and 48% (95% CI: 11%, 97%) higher in placental malaria-exposed children. Relative to children in the lowest third, children in the highest third of cord hepcidin had on average 2.5 g/L (95% CI: 0.1, 4.8) lower hemoglobin levels over the duration of follow-up, increased risk of anemia and severe anemia (adjusted hazard ratio [HR] [95% CI]: 1.18 [1.03, 1.36] and 1.34 [1.08, 1.66], respectively), and decreased risk of malaria and all-cause mortality (adjusted HR [95% CI]: 0.78 [0.67, 0.91] and 0.34 [0.14, 0.84], respectively). Although longitudinal measurements of hepcidin and iron stores are required to strengthen causal inference, these results suggest that hepcidin may have utility as a biomarker indicating children's susceptibility to anemia and infection in early life.