Fetal iron status regulates maternal iron metabolism during pregnancy in the rat

A Large Proportion of The Neonatal Iron Pool is Acquired from the Gestational Diet in a Murine Model

BACKGROUND

Iron is crucial for growth and development, but excess iron is harmful. Neonatal mice have elevated levels of circulating iron, but the source of this iron is unclear. This lack of understanding makes it difficult to optimize early life iron balance.

OBJECTIVE

Identify the origins of neonatal tissue-specific iron pools using dietary manipulation and cross-fostering murine models.

METHODS

To determine whether tissue-specific neonatal iron was primarily acquired during gestation or after birth, pups born to iron sufficient or iron deficient dams were cross-fostered and tissues were harvested at postnatal day 3-5 (P3-5) to measure iron content. A separate set of female mice were fed a diet enriched with the stable iron isotope iron57 (57Fe) for four generations to replace naturally abundant liver iron56 (56Fe) stores with 57Fe. To quantify the proportions of neonatal iron acquired during gestation, pups born to dams with 56Fe or 57Fe stores were cross-fostered and tissues were harvested at P3-5 to determine 56Fe:57Fe ratios by inductively coupled plasma mass spectrometry (ICP-MS). Finally, to quantify the proportion of neonatal iron acquired from the maternal diet, female mice with 56Fe or 57Fe stores switched diets upon mating and pup tissues were harvested on P0 to determine 56Fe:57Fe ratios by ICP-MS.

RESULTS

Perinatal iron deficiency resulted in smaller pups and gestational iron deficiency resulted in lower neonatal serum and liver iron. Cross-fostering between dams with 56Fe and 57Fe stores demonstrated that up to 70% of neonatal serum, liver and brain iron were acquired during gestation. Dietary manipulation experiments using dams with 56Fe and 57Fe stores showed that over half of neonatal serum, liver and brain iron were from the dam's gestational diet rather than pre-conception iron stores.

CONCLUSIONS

This study provides quantitative values for the sources of neonatal iron, which may inform approaches to optimize neonatal iron status.

Impact of litter size on the hematological and iron status of gilts, sows and newborn piglets: a comparative study of domestic pigs and wild boars

BACKGROUND

The critically low hepatic iron stores of newborn piglets are considered to be a major cause of neonatal iron deficiency in modern breeds of domestic pig (Sus domestica). The main factor believed to contribute to this phenomenon is large litter size, which has been an objective of selective breeding of pigs for decades. As consequence, iron transferred from the pregnant sow has to be distributed among a greater number of fetuses.

RESULTS

Here, we investigated whether litter size influences red blood cell (RBC) indices and iron parameters in Polish Large White (PLW) piglets and gilts. Small and large litters were produced by the transfer of different numbers of embryos, derived from the same superovulated donor females, to recipient gilts. Piglets from large litters obtained following routine artificial insemination were also examined. Our results clearly demonstrated that varying the number of piglets in a litter did not affect the RBC and iron status of 1-day-old piglets, with all showing iron deficiency anemia. In contrast, gilts with small litters displayed higher RBC and iron parameters compared to mothers with large litters. A comparative analysis of the RBC status of wild boars (having less than half as many piglets per litter as domestic pigs) and PLW pigs, demonstrated higher RBC count, hemoglobin level and hematocrit value of both wild boar sows and piglets, even compared to small-litter PLW animals.

CONCLUSIONS

These findings provide evidence that RBC and iron status in newborn PLW piglets are not primarily determined by litter size, and indicate the need to study the efficiency of iron transport across the placenta in domestic pig and wild boar females.

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.

Iron Homeostasis During Pregnancy: Maternal, Placental, and Fetal Regulatory Mechanisms

Pregnancy entails a large negative balance of iron, an essential micronutrient. During pregnancy, iron requirements increase substantially to support both maternal red blood cell expansion and the development of the placenta and fetus. As insufficient iron has long been linked to adverse pregnancy outcomes, universal iron supplementation is common practice before and during pregnancy. However, in high-resource countries with iron fortification of staple foods and increased red meat consumption, the effects of too much iron supplementation during pregnancy have become a concern because iron excess has also been linked to adverse pregnancy outcomes. In this review, we address physiologic iron homeostasis of the mother, placenta, and fetus and discuss perturbations in iron homeostasis that result in pathological pregnancy. As many mechanistic regulatory systems have been deduced from animal models, we also discuss the principles learned from these models and how these may apply to human pregnancy.

The effect of iron supplementation on maternal iron deficiency anemia does not differ by baseline anemia type among Tanzanian pregnant women without severe iron deficiency anemia

PURPOSE

Whether anemia type modifies the risk of pregnancy and newborn outcomes and the effectiveness of iron supplementation is unclear. We examined the association of iron deficiency anemia (IDA) and non-iron deficiency anemia (NIDA) on the risks of these outcomes and the extent to which anemia type modifies the impact of prenatal iron supplementation.

METHODS

This was a secondary analysis of a placebo-controlled trial of iron supplementation among 1450 HIV-negative women in Tanzania. Eligibility criteria included gestational age < 27 weeks, hemoglobin > 85 g/L, and ferritin > 12 µg/L. Individuals were categorized as non-anemia, IDA or NIDA using hemoglobin, ferritin and CRP. Analyses were conducted using regression models and likelihood ratio tests.

RESULTS

Compared to the non-anemia group, delivery hemoglobin was lower by 15 g/L (95% CI 10.9, 19.3) in the baseline IDA group, and 7.3 g/L (95% CI 3.1, 11.5) in the baseline NIDA group. The RRs of anemia severity, iron deficiency, placental malaria, stillbirths, perinatal mortality, birthweight, and preterm birth were not different among women in the baseline NIDA group (vs. non-anemia) compared to the baseline IDA group (vs. non-anemia). The difference in the mean delivery hemoglobin for iron supplementation and placebo arms was 8 g/L (95% CI 6, 11) in the non-anemia group, 7 g/L (95% CI 2, 13) in the NIDA group, and 16 g/L (95% CI 10, 22) in the IDA group.

CONCLUSION

Iron supplementation is effective even among pregnant women with NIDA.

TRIAL REGISTRATION

NCT01119612 (May 7, 2010).

Fetal Alcohol Spectrum Disorder and Iron Homeostasis

Prenatal alcohol exposure results in a spectrum of behavioral, cognitive, and morphological abnormalities collectively referred to as fetal alcohol spectrum disorder (FASD). FASD presents with significant phenotypic variability and may be modified by gestational variables such as maternal nutritional status. Iron serves a critical function in the development of and processes within central nervous system (CNS) structures. Gestational iron deficiency alters CNS development and may contribute to neurodevelopmental impairment in FASD. This review explores the relationship between iron deficiency and fetal alcohol spectrum disorder as described in small animal and human studies. Consideration is given to the pathophysiologic mechanisms linking iron homeostasis and prenatal alcohol exposure. Existing data suggest that iron deficiency contributes to the severity of FASD and provide a mechanistic explanation linking these two conditions.

Erythropoietin-driven dynamic proteome adaptations during erythropoiesis prevent iron overload in the developing embryo

Erythropoietin (Epo) ensures survival and proliferation of colony-forming unit erythroid (CFU-E) progenitor cells and their differentiation to hemoglobin-containing mature erythrocytes. A lack of Epo-induced responses causes embryonic lethality, but mechanisms regulating the dynamic communication of cellular alterations to the organismal level remain unresolved. By time-resolved transcriptomics and proteomics, we show that Epo induces in CFU-E cells a gradual transition from proliferation signature proteins to proteins indicative for differentiation, including heme-synthesis enzymes. In the absence of the Epo receptor (EpoR) in embryos, we observe a lack of hemoglobin in CFU-E cells and massive iron overload of the fetal liver pointing to a miscommunication between liver and placenta. A reduction of iron-sulfur cluster-containing proteins involved in oxidative phosphorylation in these embryos leads to a metabolic shift toward glycolysis. This link connecting erythropoiesis with the regulation of iron homeostasis and metabolic reprogramming suggests that balancing these interactions is crucial for protection from iron intoxication and for survival.

Iron transport across the human placenta is regulated by hepcidin

BACKGROUND

Transport of iron across the placenta is critical for appropriate development of the fetus. Iron deficiency during pregnancy remains a major public health concern, particularly in low- and middle-income countries, often exacerbated by infectious diseases leading to altered iron trafficking via inflammatory responses. Herein, we investigate the role of hepcidin, a master regulator of iron homeostasis, on regulation of iron transport across trophoblast cells.

METHODS

We utilized the Jeg-3 choriocarcinoma cell line for analysis of the expression of transferrin receptor, ferritin, and ferroportin as well as the export of ⁵⁹Fe in the presence of hepcidin. Placental tissue from human term pregnancies was utilized for immunohistochemistry.

RESULTS

Hepcidin treatment of Jeg-3 cells decreased the expression of ferroportin and transferrin receptor (TfR) and reduced the cellular export of iron. Lower expression of TfR on the syncytiotrophoblast was associated with the highest levels of hepcidin in maternal circulation, and ferroportin expression was positively associated with placental TfR. Placentas from small-for-gestational-age newborns had significantly lower levels of ferroportin and ferritin gene expression at delivery.

CONCLUSIONS

Our data suggest that hepcidin plays an important role in the regulation of iron transport across the placenta, making it a critical link in movement of iron into fetal circulation.

IMPACT

Hepcidin has a direct impact on iron transport across the human placenta. This study provides the first evidence of direct regulation of iron efflux from human trophoblast cells by hepcidin. These data extend our understanding of iron transport across the maternal-fetal interface, a process critical for fetal health and development.

Placental Iron Content Is Lower than Previously Estimated and Is Associated with Maternal Iron Status in Women at Greater Risk of Gestational Iron Deficiency and Anemia

BACKGROUND

Based on limited data, it is estimated that the placenta retains 90 mg of iron. Little is known about determinants of placental iron content. Animal data indicate that the placenta prioritizes iron for its own needs, but this hypothesis has not been evaluated in humans.

OBJECTIVES

To characterize placental iron content and placental iron concentration (p[Fe]) in pregnant women at risk of iron insufficiency and identify determinants of p[Fe].

METHODS

Placentas were collected from 132 neonates born to teens carrying singletons (≤18 y) and 101 neonates born to 48 women carrying multiples (20-46 y). Maternal and neonatal iron status indicators [hemoglobin, serum ferritin (SF), soluble transferrin receptor (sTfR), serum iron, total body iron (TBI)] and hormones (erythropoietin, hepcidin) were measured. p[Fe] was measured using inductively coupled plasma-mass spectrometry. Correlation analyses and mixed-effects models were constructed to identify determinants of p[Fe].

RESULTS

Mean placental iron content was 23 mg per placenta (95% CI: 15, 33 mg) in the multiples and 40 mg (95% CI: 31, 51 mg) in the teens (P = 0.03). Mean p[Fe] did not differ between the cohorts. p[Fe] was higher in anemic (175 μg/g; 95% CI: 120, 254 μg/g) compared with nonanemic (46 μg/g; 95% CI: 26, 82 μg/g) women carrying multiples (P = 0.009), but did not differ between anemic (62 μg/g; 95% CI: 40, 102 μg/g) and nonanemic (73 μg/g; 95% CI: 56, 97 μg/g) teens. In women carrying multiples, low maternal iron status [lower SF (P = 0.002) and lower TBI (P = 0.01)] was associated with higher p[Fe], whereas in teens, improved iron status [lower sTfR (P = 0.03) and higher TBI (P = 0.03)] was associated with higher p[Fe].

CONCLUSIONS

Placental iron content was ∼50% lower than previously estimated. p[Fe] is significantly associated with maternal iron status. In women carrying multiples, poor maternal iron status was associated with higher p[Fe], whereas in teens, improved iron status was associated with higher p[Fe]. More data are needed to understand determinants of p[Fe] and the variable iron partitioning in teens compared with mature women.

Maternal Iron Deficiency Alters Trophoblast Differentiation and Placental Development in Rat Pregnancy

Iron deficiency, which occurs when iron demands chronically exceed intake, is prevalent in pregnant women. Iron deficiency during pregnancy poses major risks for the baby, including fetal growth restriction and long-term health complications. The placenta serves as the interface between a pregnant mother and her baby, and it ensures adequate nutrient provisions for the fetus. Thus, maternal iron deficiency may impact fetal growth and development by altering placental function. We used a rat model of diet-induced iron deficiency to investigate changes in placental growth and development. Pregnant Sprague-Dawley rats were fed either a low-iron or iron-replete diet starting 2 weeks before mating. Compared with controls, both maternal and fetal hemoglobin were reduced in dams fed low-iron diets. Iron deficiency decreased fetal liver and body weight, but not brain, heart, or kidney weight. Placental weight was increased in iron deficiency, due primarily to expansion of the placental junctional zone. The stimulatory effect of iron deficiency on junctional zone development was recapitulated in vitro, as exposure of rat trophoblast stem cells to the iron chelator deferoxamine increased differentiation toward junctional zone trophoblast subtypes. Gene expression analysis revealed 464 transcripts changed at least 1.5-fold (P < 0.05) in placentas from iron-deficient dams, including altered expression of genes associated with oxygen transport and lipoprotein metabolism. Expression of genes associated with iron homeostasis was unchanged despite differences in levels of their encoded proteins. Our findings reveal robust changes in placentation during maternal iron deficiency, which could contribute to the increased risk of fetal distress in these pregnancies.

Advances in understanding the crosstalk between mother and fetus on iron utilization

A full-term pregnancy comes with significant demand for iron. Not meeting this demand has adverse effects on maternal health and on the intrauterine and postnatal development of the infant. In the infant, some of these adverse effects cannot be reversed by postnatal iron supplementation, highlighting the need to tackle iron deficiency in utero. Achieving this requires sound understanding of the pathways that govern iron transfer at the fetomaternal interface. Two pathways are emerging as key players in this context; the hepcidin/ferroportin axis pathway and the iron regulatory protein (IRPs) pathway. In late gestation, suppression of maternal hepcidin, by as yet unknown factors, is required for increasing iron availability to the growing fetus. In the placenta, the rate of iron uptake by transferrin receptor TfR1 at the apical/maternal side and of iron release by ferroportin FPN at the basal/fetal side is controlled by IRP1. In fetal hepatocytes, build up of fetal iron stores requires post-translational inhibition of FPN by the cell-autonomous action of hepcidin. In the fetal liver, FPN is also subject to additional control at the transcriptional level, possibly by the action of hypoxia-inducible factor HIF2α. The rates of apical iron uptake and basal iron release in the placenta are modulated according to iron availability in the maternal blood and the placenta's own needs. This placental modulation ensures that the amount of iron delivered to the fetal circulation is maintained within a normal range, even in the face of mild maternal iron deficiency or overload. However, when maternal iron deficiency or overload are extreme, placental modulation is not sufficient to maintain normal iron supply to the fetus, resulting in fetal iron deficiency and overload respectively. Thus, the rate of iron transfer at the fetomaternal interface is subject to several regulatory signals operating simultaneously in the maternal liver, the placenta and the fetal liver. These regulatory signals act in concert to maintain normal iron supply to the fetus within a wide range of maternal iron states, but fail to do so when maternal iron deficiency or overload are extreme. The limitations of existing experimental models must be overcome if we are to gain better understanding of the role of these regulatory signals in normal and complicated pregnancy. Ultimately, that understanding could help identify better markers of fetal iron demand and underpin novel iron replacement strategies to treat maternal and fetal iron deficiency.

Marginally reduced maternal hepatic and splenic ferroportin under severe nutritional iron deficiency in pregnancy maintains systemic iron supply

The demand for iron is high in pregnancy to meet the increased requirements for erythropoiesis. Even pregnant females with initially iron‐replete stores develop iron‐deficiency anemia, due to inadequate iron absorption. In anemic females, the maternal iron supply is dedicated to maintaining iron metabolism in the fetus and placenta. Here, using a mouse model of iron deficiency in pregnancy, we show that iron recycled from senescent erythrocytes becomes a predominant source of this microelement that can be transferred to the placenta in females with depleted iron stores. Ferroportin is a key protein in the molecular machinery of cellular iron egress. We demonstrate that under iron deficiency in pregnancy, levels of ferroportin are greatly reduced in the duodenum, placenta and fetal liver, but not in maternal liver macrophages and in the spleen. Although low expression of both maternal and fetal hepcidin predicted ferroportin up‐regulation in examined locations, its final expression level was very likely correlated with tissue iron status. Our results argue that iron released into the circulation of anemic females is taken up by the placenta, as evidenced by high expression of iron importers on syncytiotrophoblasts. Then, a substantial decrease in levels of ferroportin on the basolateral side of syncytiotrophoblasts, may be responsible for the reduced transfer of iron to the fetus. As attested by the lowest decrease in iron content among analyzed tissues, some part is retained in the placenta. These findings confirm the key role played by ferroportin in tuning iron turnover in iron‐deficient pregnant mouse females and their fetuses.

Impact of maternal iron deficiency anaemia on the expression of the newly discovered multi-copper ferroxidase, Zyklopen, in term placentas

In the present study, we investigated the effect of maternal iron deficiency anaemia (IDA) on expression of the newly discovered iron transporter, Zyklopen in term placenta, in 200 pregnant women. Placental expression of Zyklopen was studied by mRNA analysis and immunohistochemistry for the protein. In addition neonatal anthropometric parameters were also analysed. 58.8% of 200 subjects were anaemic. Both Zyklopen mRNA as well as protein expression in the placenta showed a statistically significant increase with increasing severity of anaemia. Although all the neonatal anthropometric parameters were lower in newborns of anaemic mothers, none showed any statistical significance. Zp mRNA levels did not show any significant correlation with newborn and placental parameters (except newborn skinfold thickness and head circumference). Similar to mRNA expression, Zp IHC expression correlated positively, albiet non-significantly, with newborn length and Hb levels, the correlation was however negative with birth weight, head circumference, mid-arm circumference unlike the mRNA expression, where it positively correlated with the above parameters. Our study for the first time demonstrated a definite increase in expression of Zyklopen at both mRNA and protein levels in term placenta, in maternal IDA.IMPACT STATEMENTWhat is already known on this subject? Iron deficiency anaemia (IDA) in a pregnant mother can lead to anaemia in the developing foetus; which is frequently observed to be of lesser severity than that in the mother. Recently a copper-containing oxidase called Zyklopen was discovered which was involved in iron efflux in BeWo cells. The gene encoding Zyklopen has been identified with a putative C-terminal membrane-spanning sequence and high sequence identitical to hephaestin (Heph) and ceruloplasmin (Cp), the other known vertebrate multicopper ferroxidase (MCF). Protein expression of this new MCF was observed in multiple diverse mouse tissues, including placenta and mammary gland.What do the results of this study add? Zyklopen protein immunohistochemical expression showed a statistically significant increase with increasing severity of anaemia. Similarly, placental mRNA expression of the Zyklopen gene was observed to be higher in anaemic mothers when compared to non-anaemic mothers. Our study for the first time demonstrated a definite increase in expression of Zyklopen at both protein and mRNA levels in term placenta, in maternal IDA.What are the implications of these findings for clinical practice and/or further research? This study will help us to understand better, the increased potential for influx of iron from mother to foetus in the condition of maternal iron deficiency. This study will help to determine how placental iron transport proteins can be regulated in response to maternal and neonatal iron status and will further our existing knowledge on relationships between maternal and neonatal iron status and mechanisms by which placental iron transport is modified in relation to these parameters.

Hypoxia-inducible factor-1α, hepcidin and interleukin-6 levels in pregnancies with preterm labour

The aim of the study was to investigate whether serum hypoxia-inducible factor-1alpha (HIF-1α), hepcidin and interleukin-6 (IL-6) concentrations differed between threatened preterm labour (TPL) and uncomplicated pregnancies. This study was conducted on 54 women with TDL pregnancies and 26 healthy pregnant women. The TPL group was further divided into two subgroups according to the gestational age at delivery. Patients who gave birth within 48-72 h after the hospitalisation were referred to as preterm delivery (PD) and who gave birth at ≥37 weeks were referred to as term delivery (TD). Maternal levels of serum HIF-1α, hepcidin and IL-6 were measured with the use of enzyme-linked immunosorbent assay kits. The mean maternal serum HIF-1α, hepcidin and IL-6 levels of PD were significantly higher than TD (p < .001*) and control group (p < .001*). The mean maternal serum HIF-1α and hepcidin levels of TD were no significantly higher than the control group (p=.058, p = .064). The mean maternal serum IL-6 level of TD was significantly higher than the control group (p < .001*). A negative correlation was found between serum concentration of HIF1α, hepcidin, IL-6 with the gestational week of delivery (r = -0.421, p < .01* for HIF-1α; r = -0.578, p < .01* for hepcidin and r = -0.435, p < .01* for IL-6). High levels of HIF-1α, hepcidin and IL-6 may have potential to be used as biomarkers for the differentiation of PD and TD.Impact statementWhat is already known on this subject? It is known that hypoxia-inducible factor-1alpha (HIF-1α) is a hypoxia marker and hepcidin and interleukin-6 (IL-6) increase in inflammation. Our study is the comparison of maternal serum HIF-1α, hepcidin and IL-6 levels between the TPL group (TD and PD) and healthy control group.What the results of this study add? The present study demonstrates that serum HIF-1α, hepcidin and IL-6 levels were significantly higher in TPD group than uncomplicated group. The mean maternal serum HIF-1α and hepcidin levels of TD were no significantly higher than the control group.What the implications are of these findings for clinical practice and/or further research? High levels of HIF-1α, hepcidin and IL-6 may be biomarkers in the determination of true preterm labour within the TPL group.

Iron deficiency during pregnancy and lactation modifies the fatty acid composition of the brain of neonatal rats

Iron deficiency is common in pregnant and lactating women and is associated with reduced cognitive development of the offspring. Since iron affects lipid metabolism, the availability of fatty acids, particularly the polyunsaturated fatty acids required for early neural development, was investigated in the offspring of female rats fed iron-deficient diets during gestation and lactation. Subsequent to the dams giving birth, one group of iron-deficient dams was recuperated by feeding an iron-replete diet. Dams and neonates were killed on postnatal days 1, 3 and 10, and the fatty acid composition of brain and stomach contents was assessed by gas chromatography. Changes in the fatty acid profile on day 3 became more pronounced on day 10 with a decrease in the proportion of saturated fatty acids and a compensatory increase in monounsaturated fatty acids. Long-chain polyunsaturated fatty acids in the n-6 family were reduced, but there was no change in the n-3 family. The fatty acid profiles of neonatal brain and stomach contents were similar, suggesting that the change in milk composition may be related to the changes in the neonatal brain. When the dams were fed an iron-sufficient diet at birth, the effects of iron deficiency on the fatty acid composition of lipids in both dam's milk and neonates' brains were reduced. This study showed an interaction between maternal iron status and fatty acid composition of the offspring's brain and suggests that these effects can be reduced by iron repletion of the dam's diet at birth.

Maternal anemia type during pregnancy is associated with anemia risk among offspring during infancy

BACKGROUND

We evaluated the association between etiology of maternal anemia and iron status throughout infancy.

METHODS

Samples from a study designed to examine Praziquantel treatment during pregnancy were used (n = 359). All women were infected with schistosomiasis and randomized to Praziquantel or placebo at 16 ± 2 weeks' gestation. Hemoglobin, serum ferritin (SF), soluble transferrin receptor (sTfR), hepcidin, C-reactive protein, and interleukin-6 were measured in maternal and infant blood. The relationship between both maternal Praziquantel treatment and etiology of anemia and infant iron status was evaluated.

RESULTS

Maternal iron-deficiency anemia was associated with increased risk of infant anemia at 6 months of age. Infants of mothers with the lowest levels of circulating hepcidin during gestation, likely a marker for iron deficiency, had higher sTfR:SF levels and lower hemoglobin levels, particularly at 12 months of age. Maternal non-iron-deficiency anemia (NIDA) did not impact infant anemia risk or iron status. Maternal treatment for schistosomiasis had no effect on infant hematologic status.

CONCLUSIONS

Maternal iron deficiency anemia was associated with an increased risk for anemia or iron deficiency during late infancy. We did not observe an association between maternal NIDA and increased risk for iron deficiency during infancy.

Glycosylation Profile of the Transferrin Receptor in Gestational Iron Deficiency and Early-Onset Severe Preeclampsia

Objective

To examine the expression of hypoxia-inducible factor-1α (HIF-1α), TfR1, and TfR1-attached terminal monosaccharides in placentas of women with IDAP and severe preeclampsia.

Methods

TfR1 and HIF-1α were detected by western blot. Immunoadsorption of TfR1 was performed to characterize the terminal monosaccharides by specific lectin binding.

Results

There was no difference in the expression of TfR1 and HIF-1α between groups. Lectin blot analysis pointed out an overexpression of galactose β1-4 N-acetylglucosamine (Gal-GlcNAc) and mannose in severe preeclampsia.

Conclusion

The increase in Gal-GlcNAc may be due to the increased presence of antennary structures and the mannose glycans of TfR1 may indicate the presence of misfolded or incomplete proteins. These findings may be associated with the low expression of placental TfR1 in women with preeclampsia.

Biomarkers of Nutrition for Development (BOND)-Iron Review

This is the fifth in the series of reviews developed as part of the Biomarkers of Nutrition for Development (BOND) program. The BOND Iron Expert Panel (I-EP) reviewed the extant knowledge regarding iron biology, public health implications, and the relative usefulness of currently available biomarkers of iron status from deficiency to overload. Approaches to assessing intake, including bioavailability, are also covered. The report also covers technical and laboratory considerations for the use of available biomarkers of iron status, and concludes with a description of research priorities along with a brief discussion of new biomarkers with potential for use across the spectrum of activities related to the study of iron in human health.The I-EP concluded that current iron biomarkers are reliable for accurately assessing many aspects of iron nutrition. However, a clear distinction is made between the relative strengths of biomarkers to assess hematological consequences of iron deficiency versus other putative functional outcomes, particularly the relationship between maternal and fetal iron status during pregnancy, birth outcomes, and infant cognitive, motor and emotional development. The I-EP also highlighted the importance of considering the confounding effects of inflammation and infection on the interpretation of iron biomarker results, as well as the impact of life stage. Finally, alternative approaches to the evaluation of the risk for nutritional iron overload at the population level are presented, because the currently designated upper limits for the biomarker generally employed (serum ferritin) may not differentiate between true iron overload and the effects of subclinical inflammation.

Effects of micronutrients on placental function: evidence from clinical studies to animal models

Micronutrient deficiencies are common in pregnant women due to low dietary intake and increased requirements for fetal development. Low maternal micronutrient status is associated with a range of pregnancy pathologies involving placental dysfunction, including fetal growth restriction (FGR), small-for-gestational age (SGA), pre-eclampsia and preterm birth. However, clinical trials commonly fail to convincingly demonstrate beneficial effects of supplementation of individual micronutrients, attributed to heterogeneity and insufficient power, potential interactions and lack of mechanistic knowledge of effects on the placenta. We aimed to provide current evidence of relationships between selected micronutrients (vitamin D, vitamin A, iron, folate, vitamin B12) and adverse pregnancy outcomes, combined with understanding of actions on the placenta. Following a systematic literature search, we reviewed data from clinical, in vitro and in vivo studies of micronutrient deficiency and supplementation. Key findings are potential effects of micronutrient deficiencies on placental development and function, leading to impaired fetal growth. Studies in human trophoblast cells and rodent models provide insights into underpinning mechanisms. Interestingly, there is emerging evidence that deficiencies in all micronutrients examined induce a pro-inflammatory state in the placenta, drawing parallels with the inflammation detected in FGR, pre-eclampsia, stillbirth and preterm birth. Beneficial effects of supplementation are apparent in vitro and in animal models and for combined micronutrients in clinical studies. However, greater understanding of the roles of these micronutrients, and insight into their involvement in placental dysfunction, combined with more robust clinical studies, is needed to fully ascertain the potential benefits of supplementation in pregnancy.

Dietary Iron Fortification Normalizes Fetal Hematology, Hepcidin, and Iron Distribution in a Rat Model of Prenatal Alcohol Exposure

BACKGROUND

Prenatal alcohol exposure (PAE) causes neurodevelopmental disability. Clinical and animal studies show gestational iron deficiency (ID) exacerbates PAE's behavioral and growth deficits. In rat, PAE manifests an inability to establish iron homeostasis, increasing hepcidin (maternal and fetal), and fetal liver iron while decreasing brain iron and promoting anemia. Here, we hypothesize dietary iron fortification during pregnancy may mitigate alcohol's disruption of fetal iron homeostasis.

METHODS

Pregnant Long-Evans rats, fed iron-sufficient (100 ppm iron) or iron-fortified (IF; 500 ppm iron) diets, received either 5 g/kg alcohol (PAE) or isocaloric maltodextrin daily on gestational days (GD) 13.5 through 19.5. Maternal and fetal outcomes were evaluated on GD20.5.

RESULTS

PAE reduced mean fetal weight (p < 0.001) regardless of maternal iron status, suggesting iron fortification did not improve fetal growth. Both PAE (p < 0.01) and IF (p = 0.035) increased fetal liver iron. In fetal brain, PAE (p = 0.015) affected total (p < 0.001) and nonheme iron (p < 0.001) such that iron fortification normalized (p = 0.99) the alcohol-mediated reductions in brain iron and nonheme iron. Iron fortification also improved fetal hematologic indices in PAE including hemoglobin, hematocrit, and mean cell volume (ps<0.001). Iron fortification also normalized hepcidin expression in alcohol-exposed maternal and fetal liver. Neither diet nor PAE affected transferrin (Tf) and ferritin (FTN) content in fetal liver, nor Tf or transferrin receptor in fetal brain. However, IF-PAE fetal brains trended to less FTN content (p = 0.074), suggesting greater availability of nonstorage iron. In PAE, hepcidin levels were linearly related to increased liver iron stores and decreased red blood cell count and brain iron.

CONCLUSIONS

Maternal oral iron fortification mitigated PAE's disruption of fetal iron homeostasis and improved brain iron content, hematologic indices, and hepcidin production in this rat PAE model. Clinical studies show maternal ID substantially enhances fetal vulnerability to PAE, and our work supports increased maternal dietary iron intake may improve fetal iron status in alcohol-exposed pregnancies.

Maternal iron nutriture as a critical modulator of fetal alcohol spectrum disorder risk in alcohol-exposed pregnancies

Alcohol consumption during pregnancy places the fetus at risk for permanent physical, cognitive, and behavioral impairments, collectively termed fetal alcohol spectrum disorder (FASD). However, prenatal alcohol exposure (PAE) outcomes vary widely, and growing evidence suggests that maternal nutrition is a modifying factor. Certain nutrients, such as iron, may modulate FASD outcomes. Untreated gestational iron deficiency (ID) causes persistent neurodevelopmental deficits in the offspring that affect many of the same domains damaged by PAE. Although chronic alcohol consumption enhances iron uptake and elevates liver iron stores in adult alcoholics, alcohol-abusing premenopausal women often have low iron reserves due to menstruation, childbirth, and poor diet. Recent investigations show that low iron reserves during pregnancy are strongly associated with a worsening of several hallmark features in FASD including reduced growth and impaired associative learning. This review discusses recent clinical and animal model findings that maternal ID worsens fetal outcomes in response to PAE. It also discusses underlying mechanisms by which PAE disrupts maternal and fetal iron homeostasis. We suggest that alcohol-exposed ID pregnancies contribute to the severe end of the FASD spectrum.

Anemia of Inflammation during Human Pregnancy Does Not Affect Newborn Iron Endowment

Background

To our knowledge, no studies have addressed whether maternal anemia of inflammation (AI) affects newborn iron status, and few have addressed risk factors for specific etiologies of maternal anemia.

Objectives

The study aims were to evaluate 1) the contribution of AI and iron deficiency anemia (IDA) to newborn iron endowment, 2) hepcidin as a biomarker to distinguish AI from IDA among pregnant women, and 3) risk factors for specific etiologies of maternal anemia.

Methods

We measured hematologic biomarkers in maternal blood at 12 and 32 wk of gestation and in cord blood from a randomized trial of praziquantel in 358 pregnant women with Schistosoma japonicum in The Philippines. IDA was defined as anemia with serum ferritin <30 ng/mL and non-IDA (NIDA), largely due to AI, as anemia with ferritin ≥30 ng/mL. We identified cutoffs for biomarkers to distinguish IDA from NIDA by using area under the curve (AUC) analyses and examined the impact of different causes of anemia on newborn iron status (primary outcome) by using multivariate regression modeling.

Results

Of the 358 mothers, 38% (n = 136) had IDA and 9% (n = 32) had NIDA at 32 wk of gestation. At 32 wk of gestation, serum hepcidin performed better than soluble transferrin receptor (sTfR) in identifying women with NIDA compared with the rest of the cohort (AUCs: 0.75 and 0.70, respectively) and in identifying women with NIDA among women with anemia (0.73 and 0.72, respectively). The cutoff that optimally distinguished women with NIDA from women with IDA in our cohort was 6.1 µg/L. Maternal IDA, but not NIDA, was associated with significantly lower newborn ferritin (114.4 ng/mL compared with 148.4 µg/L; P = 0.042).

Conclusions

Hepcidin performed better than sTfR in identifying pregnant women with NIDA, but its cost may limit its use. Maternal IDA, but not NIDA, is associated with decreased newborn iron stores, emphasizing the need to identify this cause and provide iron therapy. This trial was registered at www.clinicaltrials.gov as NCT00486863.

Maternal serum levels and placental expression of hepcidin in preeclampsia

Preeclampsia (PE) is a multifactorial pregnancy-induced syndrome and infection could have a role in its etiopathogenesis. Hepcidin, central regulator of iron homeostasis, is an antimicrobial peptide induced by inflammatory/infective stimuli. Therefore, hepcidin could be a good nonspecific marker of infection in PE. In a cross-sectional study, we assessed maternal serum levels (ELISA) and placental expression (Real-Time PCR and ELISA) of hepcidin in PE and normal pregnancies. In a prospective study, hepcidin maternal serum levels were assessed in early pregnancy before PE onset and in age matched controls. Hepcidin protein and gene expressions were significantly decreased in PE placentae with normal fetal growth compared to controls and PE with Fetal Growth Restriction (FGR), respectively. In contrast, we did not find significant differences in maternal serum hepcidin levels in PE vs gestational age-matched controls. Hepcidin serum levels in the first half of pregnancy were found significantly higher in women who subsequently developed PE compared to mothers having a physiological pregnancy until term. Altered hepcidin expression in PE placentae could be explained by direct infective/inflammatory stimuli. Furthermore, high hepcidin levels in maternal serum could be an early marker of PE, further emphasizing the role of inflammatory status before symptoms onset in PE.

Iron homeostasis during pregnancy

During pregnancy, iron needs to increase substantially to support fetoplacental development and maternal adaptation to pregnancy. To meet these iron requirements, both dietary iron absorption and the mobilization of iron from stores increase, a mechanism that is in large part dependent on the iron-regulatory hormone hepcidin. In healthy human pregnancies, maternal hepcidin concentrations are suppressed in the second and third trimesters, thereby facilitating an increased supply of iron into the circulation. The mechanism of maternal hepcidin suppression in pregnancy is unknown, but hepcidin regulation by the known stimuli (i.e., iron, erythropoietic activity, and inflammation) appears to be preserved during pregnancy. Inappropriately increased maternal hepcidin during pregnancy can compromise the iron availability for placental transfer and impair the efficacy of iron supplementation. The role of fetal hepcidin in the regulation of placental iron transfer still remains to be characterized. This review summarizes the current understanding and addresses the gaps in knowledge about gestational changes in hematologic and iron variables and regulatory aspects of maternal, fetal, and placental iron homeostasis.

Zinc is a critical regulator of placental morphogenesis and maternal hemodynamics during pregnancy in mice

Zinc is an essential micronutrient in pregnancy and zinc deficiency impairs fetal growth. We used a mouse model of moderate zinc deficiency to investigate the physiological mechanisms by which zinc is important to placental morphogenesis and the maternal blood pressure changes during pregnancy. A 26% reduction in circulating zinc (P = 0.005) was exhibited in mice fed a moderately zinc-deficient diet. Zinc deficiency in pregnancy resulted in an 8% reduction in both near term fetal and placental weights (both P < 0.0001) indicative of disrupted placental development and function. Detailed morphological analysis confirmed changes to the placental labyrinth microstructure. Continuous monitoring of maternal mean arterial pressure (MAP) revealed a late gestation decrease in the zinc-deficient dams. Differential expression of a number of regulatory genes within maternal kidneys supported observations on MAP changes in gestation. Increased MAP late in gestation is required to maintain perfusion of multiple placentas within rodent pregnancies. Decreased MAP within the zinc-deficient dams implies reduced blood flow and nutrient delivery to the placenta. These findings show that adequate zinc status is required for correct placental morphogenesis and appropriate maternal blood pressure adaptations to pregnancy. We conclude that insufficient maternal zinc intake from before and during pregnancy is likely to impact in utero programming of offspring growth and development largely through effects to the placenta and maternal cardiovascular system.

Higher Rate of Iron Deficiency in Obese Pregnant Sudanese Women

AIM:

To assess the association between obesity and iron deficiency (ID).

MATERIAL AND METHODS:

Pregnant women were recruited from Saad Abualila Hospital, Khartoum, Sudan, during January–April 2015. Medical history (age, parity, gestational age) was gathered using questionnaire. Weight and height were measured, and body mass index (BMI) was calculated. Women were sub-grouped based on BMI into underweight (< 18.5 kg/m^2), normal weight (18.5–24.9 kg/m^2), overweight (25–29.9 kg/m^2) and obese (≥ 30 kg/m^2). Serum ferritin and red blood indices were measured in all studied women.

RESULTS:

Two (0.5%), 126 (29.8%), 224 (53.0%) and 71 (16.8%) out of the 423 women were underweight, normal weight, overweight and obese, respectively. Anemia (Hb <11 g/dl), ID (ferritin <15µg/l) and iron deficiency anemia (IDA) were prevalent in 57.7%, 21.3% and 12.1%, respectively. Compared with the women with normal BMI, significantly fewer obese women were anemic [25 (35.2%) vs. 108 (85.7%), P < 0.001] and significantly higher number of obese women [25 (35.2) vs. 22 (17.5, P = 0.015] had iron deficiency. Linear regression analysis demonstrated a significant negative association between serum ferritin and BMI (– 0.010 µg/, P= 0.006).

CONCLUSION:

It is evident from the current findings that prevalence of anaemia and ID showed different trends about BMI of pregnant women

Effects of different iron supply to pregnant sows (Sus scrofa domestica L.) on reproductive performance as well as iron status of new-born piglets

The present study aimed to investigate the effects of different iron (Fe) supply to sows during gestation on their reproductive performance and placental Fe load. Additionally, the Fe status of the corresponding offspring was assessed. Twenty multiparous sows were fed from insemination to farrowing with isoenergetic and isonitrogenic balanced diets differing in Fe content. The diet low in Fe (Group -Fe) was mainly composed of soybean meal and maize meal and had a Fe content of 114 mg/kg DM. For the diet high in Fe (Group +Fe), the diet was supplemented with Fe(II)SO₄ · 7H₂O to a total Fe content of 256 mg/kg. Blood characteristics (haemoglobin, haematocrit, mean corpuscular haem concentration, total Fe-binding capacity, transferrin saturation) of all sows were measured at the beginning and at the end of gestation. Daily Fe retention was calculated at the day of farrowing. After birth, reproductive performance (litter size, piglet weight, litter weight), placental Fe content and Fe blood characteristics of the piglets were determined. Apparent daily Fe retention tended to be greater in Group +Fe (p < 0.1). Blood parameters of the sows did not show any variations between feeding groups, neither at the beginning nor at the end of pregnancy, whereas placental Fe content was lower in Group -Fe (p < 0.05). In addition, Fe supply during gestation improved litter size (p < 0.01) and litter weight (p < 0.05). Although all sows were supplied according to the current Fe recommendations, a significant decline in reproductive performance of Group -Fe was recognised. Therefore, it was concluded that the re-evaluation of the gross Fe requirements of pregnant sows is inevitable to accommodate the current feeding recommendations.

The effect of iron deficiency on the temporal changes in the expression of genes associated with fat metabolism in the pregnant rat

Iron is essential for the oxidative metabolism of lipids. Lipid metabolism changes during gestation to meet the requirements of the growing fetus and to prepare for lactation. The temporal effects of iron deficiency during gestation were studied in female rats fed complete or iron‐deficient diets. Plasma triglycerides were elevated in the iron‐deficient group throughout gestation. There were time‐dependent changes in the triglyceride content of the maternal liver, falling at the midpoint of gestation and then increasing on d21.5. Compared to the control, triglycerides in the maternal liver were not different in the iron‐deficient group prior to pregnancy and on d12.5, but were markedly reduced by d21.5. The abundance of mRNAs in the maternal liver suggests that lipogenesis is unchanged and beta‐oxidation is reduced on d21.5 by iron deficiency. On d21.5 of gestation, the expression of placental lipase was unchanged by iron deficiency, however, the abundance of mRNAs for SREBP‐1c, FABP4 were reduced, suggesting that there were changes in fatty acid handling. In the fetal liver, iron deficiency produced a marked decrease in the abundance of the L‐CPT‐1 mRNA, suggesting that beta‐oxidation is reduced. This study shows that the major effect of iron deficiency on maternal lipid metabolism occurs late in gestation and that perturbed lipid metabolism may be a common feature of models of fetal programming.

The reproductive ecology of iron in women

Reproductive ecology focuses on the sensitivity of human reproduction to environmental variation. While reproductive ecology has historically focused on the relationship between energy status and reproductive outcomes, iron status is equally critical to women's reproductive health, given the wide-ranging detrimental effects of iron-deficiency anemia on maternal and infant well-being. This review interprets the vast literature on iron status and women's reproduction through an evolutionary framework. First, it will critique the evidence for iron deficiency caused by blood loss during menstruation, reinterpreting the available data as ecological variation in menses within and between populations of women. Second, it will highlight the scant but growing evidence that iron status is implicated in fertility, a relationship that has deep evolutionary roots. Third, this review proposes a new hypothesis for the transfer of iron from mother to infant via pregnancy and breastfeeding: reproductive iron withholding. In this hypothesis, mothers transfer iron to infants in a manner that helps infants avoid iron-mediated infection and oxidative stress, but trades off with potential risk of maternal and infant iron deficiency. Finally, this review explores two main factors that can modify the relationship between iron status and the gestation-lactation cycle: (1) the relationship between long-term reproductive effort (parity) and iron status and (2) supplementation schemes before and during pregnancy. The review concludes by suggesting continued research into iron homeostasis in women using evolutionary, ecological, and biocultural frameworks.

Maternal iron status during pregnancy compared with neonatal iron status better predicts placental iron transporter expression in humans

The placenta richly expresses nonheme and heme Fe transport proteins. To address the impact of maternal and neonatal Fe status and hepcidin on the regulation of these proteins, mRNA expression and protein abundance of nonheme and heme Fe transport proteins were evaluated in placental tissue from 154 adolescents. Regression analyses found maternal Fe status was significantly associated with multiple placental nonheme and heme transporters, whereas neonatal Fe status was related to only 3 heme transporters. Across statistical analyses, maternal Fe status was consistently associated with the placental nonheme Fe importer transferrin receptor 1 (TfR1). Protein abundance of TfR1 was related to midgestation maternal serum ferritin (SF) (β = -0.32; P = 0.005) and serum TfR (β = 0.25; P = 0.024). Protein abundance of the heme importer, proton-coupled folate transporter, was related to neonatal SF (β = 0.30; P = 0.016) and serum TfR (β = -0.46; P < 0.0001). Neonatal SF was also related to mRNA expression of the heme exporter feline leukemia virus subgroup C receptor 1 (β = -0.30; P = 0.004). In summary, maternal Fe insufficiency during pregnancy predicts increased expression of the placental nonheme Fe transporter TfR1. Associations between placental heme Fe transporters and neonatal Fe status require further study.-Best, C. M., Pressman, E. K., Cao, C., Cooper, E., Guillet, R., Yost, O. L., Galati, J., Kent, T. R., O'Brien, K. O. Maternal iron status during pregnancy compared with neonatal iron status better predicts placental iron transporter expression in humans.

Iron uptake and transport across physiological barriers

Iron is an essential element for human development. It is a major requirement for cellular processes such as oxygen transport, energy metabolism, neurotransmitter synthesis, and myelin synthesis. Despite its crucial role in these processes, iron in the ferric form can also produce toxic reactive oxygen species. The duality of iron’s function highlights the importance of maintaining a strict balance of iron levels in the body. As a result, organisms have developed elegant mechanisms of iron uptake, transport, and storage. This review will focus on the mechanisms that have evolved at physiological barriers, such as the intestine, the placenta, and the blood–brain barrier (BBB), where iron must be transported. Much has been written about the processes for iron transport across the intestine and the placenta, but less is known about iron transport mechanisms at the BBB. In this review, we compare the established pathways at the intestine and the placenta as well as describe what is currently known about iron transport at the BBB and how brain iron uptake correlates with processes at these other physiological barriers.

Prenatal Alcohol Exposure Alters Fetal Iron Distribution and Elevates Hepatic Hepcidin in a Rat Model of Fetal Alcohol Spectrum Disorders

BACKGROUND

Prenatal alcohol exposure (PAE) causes neurodevelopmental disabilities, and gestational iron deficiency (ID) selectively worsens learning and neuroanatomical and growth impairments in PAE. It is unknown why ID worsens outcomes in alcohol-exposed offspring.

OBJECTIVE

We hypothesized that PAE alters maternal-fetal iron distribution or its regulation.

METHODS

Nulliparous, 10-wk-old, Long-Evans rats were mated and then fed iron-sufficient (100 mg Fe/kg) or iron-deficient (≤4 mg Fe/kg) diets. On gestational days 13.5-19.5, dams received either 5.0 g ethanol/kg body weight (PAE) or isocaloric maltodextrin by oral gavage. On gestational day 20.5, maternal and fetal clinical blood counts, tissue mineral and iron transport protein concentrations, and hepatic hepcidin mRNA expression were determined.

RESULTS

In fetal brain and liver (P < 0.001) and in maternal liver (P < 0.005), ID decreased iron (total and nonheme) and ferritin content by nearly 200%. PAE reduced fetal bodyweight (P < 0.001) and interacted with ID (P < 0.001) to reduce it by an additional 20%. Independent of maternal iron status, PAE increased fetal liver iron (30-60%, P < 0.001) and decreased brain iron content (total and nonheme, 15-20%, P ≤ 0.050). ID-PAE brains had lower ferritin, transferrin, and transferrin receptor content (P ≤ 0.002) than ID-maltodextrin brains. PAE reduced fetal hematocrit, hemoglobin, and red blood cell numbers (P < 0.003) independently of iron status. Unexpectedly, and also independent of iron status, PAE increased maternal and fetal hepatic hepcidin mRNA expression >300% (P < 0.001).

CONCLUSIONS

PAE altered fetal iron distribution independent of maternal iron status in rats. The elevated iron content of fetal liver suggests that PAE may have limited iron availability for fetal erythropoiesis and brain development. Altered fetal iron distribution may partly explain why maternal ID substantially worsens growth and behavioral outcomes in PAE.

The placenta: the forgotten essential organ of iron transport

Optimal iron nutrition in utero is essential for development of the fetus and helps establish birth iron stores adequate to sustain growth in early infancy. In species with hemochorial placentas, such as humans and rodents, iron in the maternal circulation is transferred to the fetus by directly contacting placental syncytiotrophoblasts. Early kinetic studies provided valuable data on the initial uptake of maternal transferrin, an iron-binding protein, by the placenta. However, the remaining steps of iron trafficking across syncytiotrophoblasts and through the fetal endothelium into the fetal blood remain poorly characterized. Over the last 20 years, identification of transmembrane iron transporters and the iron regulatory hormone hepcidin has greatly expanded the knowledge of cellular iron transport and its regulation by systemic iron status. In addition, emerging human and animal data demonstrating comprised fetal iron stores in severe maternal iron deficiency challenge the classic dogma of exclusive fetal control over the transfer process and indicate that maternal and local signals may play a role in regulating this process. This review compiles current data on the kinetic, molecular, and regulatory aspects of placental iron transport and considers new questions and knowledge gaps raised by these advances.

Maternal Obesity Affects Inflammatory and Iron Indices in Umbilical Cord Blood

OBJECTIVE

To determine the impact of maternal obesity and gestational weight gain across pregnancy on fetal indices of inflammation and iron status.

STUDY DESIGN

Eighty-five healthy term newborns delivered via elective cesarean were categorized by 2 maternal body mass index (BMI) thresholds; above or below 30 kg/m(2) or above or below 35 kg/m(2). Umbilical cord plasma levels of C-reactive protein, interleukin (IL)-6, tumor necrosis factor (TNF)-α, ferritin, and hepcidin were assayed. Cytokines released by phytohemagglutinin-stimulated umbilical cord mononuclear cells (MNCs) were assayed.

RESULTS

Maternal class II obesity, defined as BMI of 35 kg/m(2) and above, predicted higher C-reactive protein and TNF-α in umbilical cord plasma (P < .05 for both), and also proinflammatory cytokines (IL-1β, IL-6, and TNF-α) from stimulated MNC (P < .05 for all). The rise in plasma TNF-α and MNC TNF-α was not linear but occurred when the threshold of BMI 35 kg/m(2) was reached (P < .005, P < .06). Poorer umbilical cord iron indices were associated with maternal obesity. When ferritin was low, IL-6 was higher (P < .04), but this relationship was present primarily when maternal BMI exceeded 35 kg/m(2) (P < .03). Ferritin was correlated with hepcidin (P < .0001), but hepcidin was unrelated to either maternal BMI or inflammatory indices.

CONCLUSIONS

Class II obesity and above during pregnancy is associated with fetal inflammation in a threshold fashion. Although maternal BMI negatively impacted fetal iron status, hepcidin, related to obesity in adults, was related to iron status and not obesity in fetuses. Pediatricians should be aware of these relationships.

Dietary-induced gestational iron deficiency inhibits postnatal tissue iron delivery and postpones the cessation of active nephrogenesis in rats

Gestational iron deficiency (ID) can alter developmental programming through impaired nephron endowment, leading to adult hypertension, but nephrogenesis is unstudied. Iron status and renal development during dietary-induced gestational ID (<6 mg Fe kg-1 diet from Gestational Day 2 to Postnatal Day (PND) 7) were compared with control rats (198 mg Fe kg-1 diet). On PND2-PND10, PND15, PND30 and PND45, blood and tissue iron status were assessed. Nephrogenic zone maturation (PND2-PND10), radial glomerular counts (RGCs), glomerular size density and total planar surface area (PND15 and PND30) were also assessed. Blood pressure (BP) was measured in offspring. ID rats were smaller, exhibiting lower erythrocyte and tissue iron than control rats (PND2-PND10), but these parameters returned to control values by PND30-PND45. Relative kidney iron (µg g-1 wet weight) at PND2-PND10 was directly related to transport iron measures. In ID rats, the maturation of the active nephrogenic zone was later than control. RGCs, glomerular size, glomerular density, and glomerular planar surface area were lower than control at PND15, but returned to control by PND30. After weaning, the kidney weight/rat weight ratio (mg g-1) was heavier in ID than control rats. BP readings at PND45 were lower in ID than control rats. Altered kidney maturation and renal adaptations may contribute to glomerular size, early hyperfiltration and long-term renal function.

Maternal obesity during pregnancy is negatively associated with maternal and neonatal iron status

Background/Objectives

Obesity among pregnant women may adversely affect both maternal iron status throughout pregnancy and placental transfer of iron. The objective of this study was to determine the association of maternal body mass index (BMI) with 1) maternal iron status and inflammation in mid and late pregnancy, 2) the change in maternal iron status throughout pregnancy, and 3) neonatal iron status.

Subjects/Methods

We examined longitudinal data from 1,613 participants in a pregnancy iron supplementation trial in rural China. Women with uncomplicated singleton pregnancies were enrolled in the early second trimester of pregnancy and followed through parturition. Maternal blood samples obtained at enrollment and in the third trimester, and cord blood samples were analyzed for a range of hematological and iron biomarkers.

Results

There was a negative association between maternal BMI and iron status at enrollment (transferrin receptor (sTfR): r=0.20, P<0.001; body iron (BI): r=−0.05; P=0.03). This association was markedly stronger among obese women. Maternal BMI was positively associated with maternal inflammation (C-reactive protein: r=0.33, P<0.001). In multiple linear regression models, maternal BMI was negatively associated with neonatal iron status (cord serum ferritin: −0.01, P=0.008; BI: −0.06, P=0.006) and associated with a lower decrease in iron status throughout pregnancy (sTfR: −4.6, P<0.001; BI: 1.1, P=0.004).

Conclusions

Maternal obesity during pregnancy may adversely affect both maternal and neonatal iron status, potentially through inflammatory pathways.

Effects of Pregnancy and Lactation on Iron Metabolism in Rats

In female, inadequate iron supply is a highly prevalent problem that often leads to iron-deficiency anemia. This study aimed to understand the effects of pregnancy and lactation on iron metabolism. Rats with different days of gestation and lactation were used to determine the variations in iron stores and serum iron level and the changes in expression of iron metabolism-related proteins, including ferritin, ferroportin 1 (FPN1), ceruloplasmin (Cp), divalent metal transporter 1 (DMT1), transferrin receptor 1 (TfR1), and the major iron-regulatory molecule—hepcidin. We found that iron stores decline dramatically at late-pregnancy period, and the low iron store status persists throughout the lactation period. The significantly increased FPN1 level in small intestine facilitates digestive iron absorption, which maintains the serum iron concentration at a near-normal level to meet the increase of iron requirements. Moreover, a significant decrease of hepcidin expression is observed during late-pregnancy and early-lactation stages, suggesting the important regulatory role that hepcidin plays in iron metabolism during pregnancy and lactation. These results are fundamental to the understanding of iron homeostasis during pregnancy and lactation and may provide experimental bases for future studies to identify key molecules expressed during these special periods that regulate the expression of hepcidin, to eventually improve the iron-deficiency status.

The Effect of Iron Deficiency on Osmotic Sensitivity of Red Blood Cells from Neonatal Rats and Their Mothers

Iron deficiency during pregnancy has many effects on both the mother and her developing foetus. These can be both short and long term. One effect is an alteration in fatty acid metabolism and we hypothesised that these changes may result in alterations in membrane function and structure. In order to test this hypothesis, we measured osmotic sensitivity in red blood cells isolated from neonates and their mothers at different times following birth. We fed female rats control or iron-deficient diets for 4 weeks prior to mating and kept them on the same diet until term. At that time, we returned one group of deficient dams to the control diet. The others were kept on the same diet. We showed that iron deficiency results in a decrease in osmotic sensitivity in the mothers but not in their neonates. Returning the dams to the control diet resulted in a return of their red cell osmotic sensitivity to control levels. In the neonates, there was no recovery in haematocrit or in any other parameter, though they did not get any worse, in contrast to the pups being suckled by deficient mothers. The data show two things. The first is that following birth, the mother restores her own iron stores at the expense of the pups, and secondly, there are differences in properties and sensitivities between red cells from mothers and their neonates. This latter observation cannot be explained by differences in the membrane fatty acid profiles, which were not significantly different.

The impact of maternal obesity on iron status, placental transferrin receptor expression and hepcidin expression in human pregnancy

BACKGROUND

Obesity is associated with decreased iron status, possibly due to a rise in hepcidin, an inflammatory protein known to reduce iron absorption. In animals, we have shown that maternal iron deficiency is minimised in the foetus by increased expression of placental transferrin receptor (pTFR1), resulting in increased iron transfer at the expense of maternal iron stores.

OBJECTIVE

This study examines the effect of obesity during pregnancy on maternal and neonatal iron status in human cohorts and whether the placenta can compensate for decreased maternal iron stores by increasing pTFR1 expression.

SUBJECTS/METHODS

A total of 240 women were included in this study. One hundred and fifty-eight placentas (Normal: 90; Overweight: 37; Obese: 31) were collected at delivery. Maternal iron status was measured by determining serum transferrin receptor (sTFR) and ferritin levels at 24 and 34 weeks and at delivery. Hepcidin in maternal and cord blood was measured by ELISA and pTFR1 in placentas by western blotting and real-time RT-PCR.

RESULTS

Low iron stores were more common in obese women. Hepcidin levels (ng ml(-1)) at the end of the pregnancy were higher in obese than normal women (26.03±12.95 vs 18.00±10.77, P<0.05). Maternal hepcidin levels were correlated with maternal iron status (sTFR r=0.2 P=0.025), but not with neonatal values. mRNA and protein levels of pTFR1 were both inversely related to maternal iron status. For mRNA and all women, sTFR r=0.2 P=0.044. Ferritin mRNA levels correlated only in overweight women r=-0.5 P=0.039 with hepcidin (r=0.1 P=0.349), irrespective of maternal body mass index (BMI).

CONCLUSIONS

The data support the hypothesis that obese pregnant women have a greater risk of iron deficiency and that hepcidin may be a regulatory factor. Further, we show that the placenta responds to decreased maternal iron status by increasing pTFR1 expression.

Antenatal iron-folic acid supplementation reduces risk of low birthweight in Pakistan: secondary analysis of Demographic and Health Survey 2006-2007

The aim of the current study was to examine the impact of antenatal iron-folic acid (IFA) supplementation on perceived birth size and birthweight in Pakistan over a 5-year period from 2002 to 2006. The data source was the Pakistan Demographic and Health Survey (PDHS) 2006-2007. Information from 5692 most recent live-born infants within 5 years prior to the survey was examined. The primary outcomes were maternal perception of birth size and birthweight, and the main exposure was any use of antenatal IFA supplements. Birthweight was reported for only 10% of the live births in the PDHS 2006-2007. Multivariate logistic regression analysis was adjusted for the cluster sampling design and for 13 potential confounders. The risk of having smaller than average birth size newborn was significantly reduced by 18% (adjusted odds ratio 0.82, 95% confidence interval 0.71, 0.96) for mothers who used any IFA supplements compared with those who did not. A similar (18%), but non-significant reduction in the risk of low birthweight, was found with the maternal use of IFA supplements. The risk of having smaller than average birth size babies was significantly reduced by 19% in those women who started IFA in the first trimester of pregnancy. About 11% of babies with smaller than average birth size were attributed to non-use of antenatal IFA supplements. Antenatal IFA supplementation significantly reduces the risk of a newborn of smaller than average birth size in Pakistan. Universal coverage of supplementation would improve birth size.

Hepcidin and iron homeostasis during pregnancy

Hepcidin is the master regulator of systemic iron bioavailability in humans. This review examines primary research articles that assessed hepcidin during pregnancy and postpartum and report its relationship to maternal and infant iron status and birth outcomes; areas for future research are also discussed. A systematic search of the databases Medline and Cumulative Index to Nursing and Allied Health returned 16 primary research articles including 10 human and six animal studies. Collectively, the results indicate that hepcidin is lower during pregnancy than in a non-pregnant state, presumably to ensure greater iron bioavailability to the mother and fetus. Pregnant women with undetectable serum hepcidin transferred a greater quantity of maternally ingested iron to their fetus compared to women with detectable hepcidin, indicating that maternal hepcidin in part determines the iron bioavailability to the fetus. However, inflammatory states, including preeclampsia, malaria infection, and obesity were associated with higher hepcidin during pregnancy compared to healthy controls, suggesting that maternal and fetal iron bioavailability could be compromised in such conditions. Future studies should examine the relative contribution of maternal versus fetal hepcidin to the control of placental iron transfer as well as optimizing maternal and fetal iron bioavailability in pregnancies complicated by inflammation.

Sleep disorders in pregnancy

Sleep disturbances are common in pregnancy and may be influenced by a multitude of factors. Pregnancy physiology may predispose to sleep disruption but may also result in worsening of some underlying sleep disorders, and the de novo development of others. Apart from sleep disordered breathing, the impact of sleep disorders on pregnancy, fetal, and neonatal outcomes is poorly understood. In this article, we review the literature and discuss available data pertaining to the most common sleep disorders in perinatal women. These include restless legs syndrome, insomnia, circadian pattern disturbances, narcolepsy, and sleep-disordered breathing.

Neonatal iron status is impaired by maternal obesity and excessive weight gain during pregnancy

OBJECTIVE

Maternal iron needs increase sixfold during pregnancy, but obesity interferes with iron absorption. We hypothesized that maternal obesity impairs fetal iron status.

STUDY DESIGN

Three hundred and sixteen newborns with risk factors for infantile iron deficiency anemia (IDA) were studied to examine obesity during pregnancy and neonatal iron status. Erythrocyte iron was assessed by cord blood hemoglobin (Hb), zinc protoporphyrin/heme (ZnPP/H) and reticulocyte-ZnPP/H, and storage iron by serum ferritin.

RESULT

Women with body mass index (BMI) ⩾ 30 kg m(-)(2), as compared with non-obese women, delivered larger offspring with higher reticulocyte-ZnPP/H and lower serum ferritin concentrations (P<0.05 for both). With increasing BMI, the estimated body iron was relatively lower (mg kg(-)(1)) and the ratio of total Hb-bound iron (mg) per total body iron (mg) increased. Maternal diabetes compromised infant iron status, but multivariate analysis demonstrated that obesity was an independent predictor.

CONCLUSION

Obesity during pregnancy and excessive weight gain are independent risk factors for iron deficiency in the newborn.

Iron overload in Plasmodium berghei-infected placenta as a pathogenesis mechanism of fetal death

Plasmodium infection during gestation may lead to severe clinical manifestations including abortion, stillbirth, intrauterine growth retardation, and low birth weight. Mechanisms underlying such poor pregnancy outcomes are still unclear. In the animal model of severe placental malaria (PM), in utero fetal death frequently occurs and mothers often succumb to infection before or immediately after delivery. Plasmodium berghei-infected erythrocytes (IEs) continuously accumulate in the placenta, where they are then phagocytosed by fetal-derived placental cells, namely trophoblasts. Inside the phagosomes, disruption of IEs leads to the release of non-hemoglobin bound heme, which is subsequently catabolized by heme oxygenase-1 into carbon monoxide, biliverdin, and labile iron. Fine-tuned regulatory mechanisms operate to maintain iron homeostasis, preventing the deleterious effect of iron-induced oxidative stress. Our preliminary results demonstrate that iron overload in trophoblasts of P. berghei-infected placenta is associated with fetal death. Placentas which supported normally developing embryos showed no iron accumulation within the trophoblasts. Placentas from dead fetuses showed massive iron accumulation, which was associated with parasitic burden. Here we present preliminary data suggesting that disruption of iron homeostasis in trophoblasts during the course of PM is a consequence of heme accumulation after intense IE engulfment. We propose that iron overload in placenta is a pathogenic component of PM, contributing to fetal death. The mechanism through which it operates still needs to be elucidated.

Placental heme receptor LRP1 correlates with the heme exporter FLVCR1 and neonatal iron status

LDL receptor-related protein 1 (LRP1) is a transmembrane receptor highly expressed in human placenta. It was recently found to be the receptor for heme and its plasma-binding protein hemopexin (Hx) and is integral to systemic heme clearance. Little is known about systemic concentrations of Hx during pregnancy and whether maternal Hx and placental LRP1 contributes to fetal iron (Fe) homeostasis during pregnancy. We hypothesized that placental LRP1 would be upregulated in maternal/neonatal Fe insufficiency and would be related to maternal circulating Hx. Placental LRP1 expression was assessed in 57 pregnant adolescents (14-18 years) in relationship with maternal and cord blood Fe status indicators (hemoglobin (Hb), serum ferritin, transferrin receptor), the Fe regulatory hormone hepcidin and serum Hx. Hx at mid-gestation correlated positively with Hb at mid-gestation (r=0.35, P=0.02) and Hx at delivery correlated positively with cord hepcidin (r=0.37, P=0.005). Placental LRP1 protein expression was significantly higher in women who exhibited greater decreases in serum Hx from mid-gestation to term (r=0.28, P=0.04). Significant associations were also found between placental LRP1 protein with cord hepcidin (r=-0.29, P=0.03) and placental heme exporter feline leukemia virus C receptor 1 (r=0.34, P=0.03). Our data are consistent with a role for placental heme Fe utilization in supporting fetal Fe demands.

Anaemia, prenatal iron use, and risk of adverse pregnancy outcomes: systematic review and meta-analysis

OBJECTIVES

To summarise evidence on the associations of maternal anaemia and prenatal iron use with maternal haematological and adverse pregnancy outcomes; and to evaluate potential exposure-response relations of dose of iron, duration of use, and haemoglobin concentration in prenatal period with pregnancy outcomes.

DESIGN

Systematic review and meta-analysis

DATA SOURCES

Searches of PubMed and Embase for studies published up to May 2012 and references of review articles.

STUDY SELECTION CRITERIA

Randomised trials of prenatal iron use and prospective cohort studies of prenatal anaemia; cross sectional and case-control studies were excluded.

RESULTS

48 randomised trials (17 793 women) and 44 cohort studies (1 851 682 women) were included. Iron use increased maternal mean haemoglobin concentration by 4.59 (95% confidence interval 3.72 to 5.46) g/L compared with controls and significantly reduced the risk of anaemia (relative risk 0.50, 0.42 to 0.59), iron deficiency (0.59, 0.46 to 0.79), iron deficiency anaemia (0.40, 0.26 to 0.60), and low birth weight (0.81, 0.71 to 0.93). The effect of iron on preterm birth was not significant (relative risk 0.84, 0.68 to 1.03). Analysis of cohort studies showed a significantly higher risk of low birth weight (adjusted odds ratio 1.29, 1.09 to 1.53) and preterm birth (1.21, 1.13 to 1.30) with anaemia in the first or second trimester. Exposure-response analysis indicated that for every 10 mg increase in iron dose/day, up to 66 mg/day, the relative risk of maternal anaemia was 0.88 (0.84 to 0.92) (P for linear trend<0.001). Birth weight increased by 15.1 (6.0 to 24.2) g (P for linear trend=0.005) and risk of low birth weight decreased by 3% (relative risk 0.97, 0.95 to 0.98) for every 10 mg increase in dose/day (P for linear trend<0.001). Duration of use was not significantly associated with the outcomes after adjustment for dose. Furthermore, for each 1 g/L increase in mean haemoglobin, birth weight increased by 14.0 (6.8 to 21.8) g (P for linear trend=0.002); however, mean haemoglobin was not associated with the risk of low birth weight and preterm birth. No evidence of a significant effect on duration of gestation, small for gestational age births, and birth length was noted.

CONCLUSIONS

Daily prenatal use of iron substantially improved birth weight in a linear dose-response fashion, probably leading to a reduction in risk of low birth weight. An improvement in prenatal mean haemoglobin concentration linearly increased birth weight.

Alcohol exposure during late ovine gestation alters fetal liver iron homeostasis without apparent dysmorphology

High levels of alcohol (ethanol) exposure during fetal life can affect liver development and can increase susceptibility to infection after birth. Our aim was to determine the effects of a moderate level of ethanol exposure in late gestation on the morphology, iron status, and inflammatory status of the ovine fetal liver. Pregnant ewes were chronically catheterized at 91 days of gestation (DG; term ∼145 DG) for daily intravenous infusion of ethanol (0.75 g/kg maternal body wt; n = 8) or saline ( n = 7) over 1 h from 95 to 133 DG. At necropsy (134 DG), fetal livers were collected for analysis. Liver weight, general liver morphology, hepatic cell proliferation and apoptosis, perivascular collagen deposition, and interleukin ( IL) -1β, IL-6, or IL-8 mRNA levels were not different between groups. However, ethanol exposure led to significant decreases in hepatic content of ferric iron and gene expression of the iron-regulating hormone hepcidin and tumor necrosis factor ( TNF) -α (all P < 0.05). In the placenta, there was no difference in transferrin receptor, divalent metal transporter 1, and ferritin mRNA levels; however, ferroportin mRNA levels were increased in ethanol-exposed animals ( P < 0.05), and ferroportin protein tended to be increased ( P = 0.054). Plasma iron concentration was not different between control and ethanol-exposed groups; control fetuses had significantly higher iron concentrations than their mothers, whereas maternal and fetal iron concentrations were similar in ethanol-exposed animals. We conclude that daily ethanol exposure during the third-trimester-equivalent in sheep does not alter fetal liver morphology; however, decreased fetal liver ferric iron content and altered hepcidin and ferroportin gene expression indicate that iron homeostasis is altered.