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

Obesogenic diet in pregnancy disrupts placental iron handling and ferroptosis and stress signalling in association with fetal growth alterations

Obesity and gestational diabetes (GDM) impact fetal growth during pregnancy. Iron is an essential micronutrient needed for energy-intense feto-placental development, but if mis-handled can lead to oxidative stress and ferroptosis (iron-dependent cell death). In a mouse model showing maternal obesity and glucose intolerance, we investigated the association of materno-fetal iron handling and placental ferroptosis, oxidative damage and stress signalling activation with fetal growth. Female mice were fed a standard chow or high fat, high sugar (HFHS) diet during pregnancy and outcomes were measured at day (d)16 or d19 of pregnancy. In HFHS-fed mice, maternal hepcidin was reduced and iron status maintained (tissue iron levels) at both d16 and d19. However, fetal weight, placental iron transfer capacity, iron deposition, TFR1 expression and ERK2-mediated signalling were reduced and oxidative damage-related lipofuscin accumulation in the placenta was increased in HFHS-fed mice. At d19, whilst TFR1 remained decreased, fetal weight was normal and placental weight, iron content and iron transporter genes (Dmt1, Zip14, and Fpn1) were reduced in HFHS-fed mice. Furthermore, there was stress kinase activation (increased phosphorylated p38MAPK, total ERK and JNK) in the placenta from HFHS-fed mice at d19. In summary, a maternal HFHS diet during pregnancy impacts fetal growth trajectory in association with changes in placental iron handling, ferroptosis and stress signalling. Downregulation of placental iron transporters in HFHS mice may protect the fetus from excessive oxidative iron. These findings suggest a role for alterations in placental iron homeostasis in determining perinatal outcomes of pregnancies associated with GDM and/or maternal obesity.

Placental ferroportin protein abundance is associated with neonatal erythropoietic activity and iron status in newborns at high risk for iron deficiency and anemia

BACKGROUND

Murine data suggest that the placenta downregulates ferroportin (FPN) when iron is limited to prioritize iron for its own needs. Human data on the impact of maternal and neonatal iron status on placental FPN expression are conflicting.

OBJECTIVES

This study aimed to identify determinants of placental FPN protein abundance and to assess the utility of the placental iron deficiency index (PIDI) as a measure of maternal/fetal iron status in newborns at high risk for anemia.

METHODS

Placental FPN protein abundance was measured by western blots in placentae collected from 133 neonates born to adolescents (17.4 ± 1.1 y) carrying singletons (delivery gestational age [GA]: 39.9 ± 1.3 wk) and from 130 neonates born to 65 females (30.4 ± 5.2 y) carrying multiples (delivery GA: 35.0 ± 2.8 wk). Placental FPN and the PIDI (FPN:transferrin receptor 1) were evaluated in relation to neonatal and maternal iron-related markers (hemoglobin [Hb], serum ferritin [SF], soluble transferrin receptor [sTfR], total body iron [TBI], hepcidin, erythropoietin [EPO], erythroferrone).

RESULTS

FPN protein was detected in all placentae delivered between 25 and 42 wk GA. Placental FPN protein abundance was associated with neonatal iron and erythropoietic markers (EPO: β: 0.10; 95% confidence interval [CI]: 0.06, 0.35; sTfR: β: 0.20; 95% CI: 0.03, 0.18; hepcidin: β: -0.06; 95% CI: -0.13, -0.0003; all P < 0.05). Maternal sTfR was only indirectly associated with placental FPN, with neonatal sTfR as the mediator (β-indirect: 0.06; 95% CI; 0.03, 0.11; P = 0.003). The PIDI was associated with neonatal Hb (β: -0.02; 95% CI: -0.03, -0.003), EPO (β: 0.07; 95% CI: 0.01, 0.14), and sTfR (β: 0.13; 95% CI: 0.004, 0.3) and with maternal SF (β: 0.08, 95% CI: 0.02, 0.14), TBI (β: 0.02; 95% CI: 0.009, 0.04), EPO (β: -0.10; 95% CI: -0.19, -0.01), sTfR (β: -0.16: 95% CI: -0.27, -0.06), and hepcidin (β: 0.05; 95% CI: 0.002, 0.11) at delivery (all P < 0.05).

CONCLUSIONS

Placental FPN abundance was positively associated with neonatal indicators of increased erythropoietic activity and poor iron status. The PIDI was associated with maternal and neonatal iron-related markers but in opposite directions. More data are needed from a lower-risk normative group of females to assess the generalizability of findings. These trials were registered at clinicaltrials.gov as NCT01019902 and NCT01582802.

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.

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.

Molecular mechanisms involved in fetal programming and disease origin in adulthood

Fetal programming occurs during the gestational age when exposure to environmental stimuli can cause long-term changes in the fetus, predisposing it to develop chronic non-communicable diseases (CNCD) in adulthood. Herein, we summarized the role of low-calorie or high-fat diets during pregnancy as fetal programming agents that induce intrauterine growth restriction (IUGR), amplified de novo lipogenesis, and increased amino acid transport to the placenta, which favor the CNCD onset in the offspring. We also outlined how maternal obesity and gestational diabetes act as fetal programming stimuli by reducing iron absorption and oxygen transport to the fetus, stimulating inflammatory pathways that boost neurological disorders and CNCD in the progeny. Moreover, we reviewed the mechanisms through which fetal hypoxia elevates the offspring's risk of developing hypertension and chronic kidney disease in adult life by unbalancing the renin-angiotensin system and promoting kidney cell apoptosis. Finally, we examined how inadequate vitamin B12 and folic acid consumption during pregnancy programs the fetus to greater adiposity, insulin resistance, and glucose intolerance in adulthood. A better understanding of the fetal programming mechanisms may help us reduce the onset of insulin resistance, glucose intolerance, dyslipidemia, obesity, hypertension, diabetes mellitus, and other CNCD in the offspring during adulthood.

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.

Maternal iron kinetics and maternal-fetal iron transfer in normal-weight and overweight pregnancy

BACKGROUND

Inflammation during pregnancy may aggravate iron deficiency (ID) by increasing serum hepcidin and reducing iron absorption. This could restrict iron transfer to the fetus, increasing risk of infant ID and its adverse effects.

OBJECTIVES

We aimed to assess whether iron bioavailability and/or iron transfer to the fetus is impaired in overweight/obese (OW) pregnant women with adiposity-related inflammation, compared with normal-weight (NW) pregnant women.

METHODS

In this prospective study, we followed NW (n = 43) and OW (n = 40) pregnant women who were receiving iron supplements from the 14th week of gestation to term and followed their infants to age 6 mo. We administered 57Fe and 58Fe in test meals mid-second and mid-third trimester, and measured tracer kinetics throughout pregnancy and infancy.

RESULTS

In total, 38 NW and 36 OW women completed the study to pregnancy week 36, whereas 30 NW and 27 OW mother-infant pairs completed the study to 6 mo postpartum. Both groups had comparable iron status, hemoglobin, and serum hepcidin throughout pregnancy. Compared with the NW, the OW pregnant women had 1) 43% lower fractional iron absorption (FIA) in the third trimester (P = 0.033) with median [IQR] FIA of 23.9% [11.4%-35.7%] and 13.5% [10.8%-19.5%], respectively; and 2) 17% lower maternal-fetal iron transfer from the first tracer (P = 0.051) with median [IQR] maternal-fetal iron transfer of 4.8% [4.2%-5.4%] and 4.0% [3.6%-4.6%], respectively. Compared with the infants born to NW women, infants born to OW women had lower body iron stores (BIS) with median [IQR] 7.7 [6.3-8.8] and 6.6 [4.6-9.2] mg/kg body weight at age 6 mo, respectively (P = 0.024). Prepregnancy BMI was a negative predictor of maternal-fetal iron transfer (β = -0.339, SE = 0.144, P = 0.025) and infant BIS (β = -0.237, SE = 0.026, P = 0.001).

CONCLUSIONS

Compared with NW, OW pregnant women failed to upregulate iron absorption in late pregnancy, transferred less iron to their fetus, and their infants had lower BIS. These impairments were associated with inflammation independently of serum hepcidin.This trial was registered at clinicaltrials.gov as NCT02747316.

Associations of the pre-pregnancy weight status with anaemia and the erythropoiesis-related micronutrient status

OBJECTIVE

The coexistence of underweight (UW) and overweight (OW)/obese (OB) at the population level is known to affect iron deficiency (ID) anaemia (IDA), but how the weight status affects erythropoiesis during pregnancy is less clear at a population scale. This study investigated associations between the pre-pregnancy BMI (pBMI) and erythropoiesis-related nutritional deficiencies.

DESIGN

Anthropometry, blood biochemistry and 24-h dietary recall data were collected during prenatal care visits. The weight status was defined based on the pBMI. Mild nutrition deficiency-related erythropoiesis was defined if individuals had an ID, folate depletion or a vitamin B12 deficiency.

SETTING

The Nationwide Nutrition and Health Survey in Taiwan (Pregnant NAHSIT 2017-2019).

PARTICIPANTS

We included 1456 women aged 20 to 45 years with singleton pregnancies.

RESULTS

Among these pregnant women, 9·6 % were UW, and 29·2 % were either OW (15·8 %) or OB (13·4 %). A U-shaped association between the pBMI and IDA was observed, with decreased odds (OR; 95 % CI) for OW subjects (0·6; 95 % CI (0·4, 0·9)) but increased odds for UW (1·2; 95 % CI (0·8, 2·0)) and OB subjects (1·2; 95 % CI (0·8, 1·8)). The pBMI was positively correlated with the prevalence of a mild nutritional deficiency. Compared to normal weight, OB pregnant women had 3·4-fold (3·4; 95 % CI (1·4, 8·1)) higher odds for multiple mild nutritional deficiencies, while UW individuals had lowest odds (0·3; 95 % CI (0·1, 1·2)). A dietary analysis showed negative relationships of pBMI with energy, carbohydrates, protein, Fe and folate intakes, but positive relationship with fat intakes.

CONCLUSION

The pre-pregnancy weight status can possibly serve as a good nutritional screening tool for preventing IDA during pregnancy.

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.

Prepregnancy Obesity Does Not Impact Placental Iron Trafficking

BACKGROUND

Iron is critical for fetal development. Neonates of obese women may be at risk for poor iron status at birth as a result of maternal inflammation-driven overexpression of hepcidin.

OBJECTIVES

The objective of this study was to determine differences in placental transfer of oral iron (57Fe) and expression of placental transferrin receptor 1 (TFR1) and ferroportin (FPN) mRNA and protein and their association with maternal and neonatal iron-related parameters, including maternal hepcidin, among women with and without prepregnancy (PP) obesity.

METHODS

57Fe ingested during the third trimester of pregnancy was recovered in venous umbilical cord blood among 20 PP obese [BMI (in kg/m2): 30.5-43.9] and 22 nonobese (BMI: 18.5-29.0) women aged 17-39 y. Placental TFR1 and FPN mRNA and protein expression were quantified via qPCR and Western blot. Maternal and neonatal markers of iron status and regulation, as well as inflammation, were measured. Descriptive and inferential statistical tests (e.g., Student t test, Pearson correlation) were used for data analysis.

RESULTS

There was no difference in cord blood enrichment of 57Fe or placental mRNA or protein expression of TFR1 or FPN among the women with and without PP obesity. Maternal hepcidin was not correlated with cord blood enrichment of 57Fe or placental FPN mRNA or protein expression. Maternal log ferritin (corrected for inflammation) was inversely correlated with log percent enrichment of 57Fe in cord blood (partial r = -0.50; P < 0.01, controlled for marital status) and protein expression of TFR1 (r = -0.43; P = 0.01).

CONCLUSIONS

Placental iron trafficking did not differ among women with and without PP obesity. Findings reinforce the importance of maternal iron stores in regulating placental iron trafficking.

Maternal Overweight and Obesity during Pregnancy Are Associated with Neonatal, but Not Maternal, Hepcidin Concentrations

BACKGROUND

Overweight or obesity among pregnant women may compromise maternal and neonatal iron status by upregulating hepcidin.

OBJECTIVES

This study determined the association of 1) maternal and neonatal iron status with maternal and neonatal hepcidin concentrations, and 2) maternal prepregnancy weight status with maternal and neonatal hepcidin concentrations.

METHODS

We examined hematologic data from 405 pregnant women and their infants from the placebo treatment group of a pregnancy iron supplementation trial in rural China. We measured hepcidin, serum ferritin (SF), soluble transferrin receptor (sTfR), and high-sensitivity C-reactive protein in maternal blood samples at mid-pregnancy and in cord blood at delivery. We used regression analysis to examine the association of maternal prepregnancy overweight or obese status with maternal hepcidin concentration in mid-pregnancy and cord hepcidin concentrations. We also used path analysis to examine mediation of the association of maternal prepregnancy overweight or obese status with maternal iron status by maternal hepcidin, as well as with neonatal hepcidin by neonatal iron status.

RESULTS

Maternal iron status was positively correlated with maternal hepcidin at mid-pregnancy (SF: r = 0.63, P < 0.001; sTfR: r = -0.37, P < 0.001). Neonatal iron status was also positively correlated with cord hepcidin (SF: r = 0.61, P < 0.001; sTfR: r = -0.39, P < 0.001). In multiple linear regression models, maternal prepregnancy overweight or obese status was not associated with maternal hepcidin at mid-pregnancy but was associated with lower cord hepcidin (coefficient = -0.21, P = 0.004). Using path analysis, we observed a significant indirect effect of maternal prepregnancy overweight or obese status on cord hepcidin, mediated by neonatal iron status.

CONCLUSIONS

In both pregnant women and neonates, hepcidin was responsive to iron status. Maternal prepregnancy overweight status, with or without including obese women, was associated with lower cord blood hepcidin, likely driven by lower iron status among the neonates of these mothers.

Lactoferrin for Prevention and Treatment of Anemia and Inflammation in Pregnant Women: A Comprehensive Review

Pregnancy is a physiological state that demands higher level of nutrients, including vitamins and minerals, for the growth and maintenance of the fetus. Iron deficiency is a part of most common diet deficiencies in pregnancy and has high clinical significance leading to the development of syderopenic anemia and its consequences for mother and child, such as higher risk of perinatal death, susceptibility to infection, intra-uteral growth inhibition, prematurity and low birth weight. Hence, iron supplementation is recommended for pregnant women; however dietary intake of iron from most commercially available formulas is often insufficient due to iron-poor bioavailability, or have undesired side-effects in the gastrointestinal tract, resulting in a discouraging and distrustful attitude to such treatment. The results of numerous studies indicate that diet supplementation with lactoferrin (LTF), an iron-binding protein, may be advantageous in prophylaxis and treatment of iron deficiency anemia. LTF, administered orally, normalizes iron homeostasis, not only by facilitating iron absorption, but also by inhibiting inflammatory processes responsible for anemia of chronic diseases, characterized by a functional iron deficit for physiological processes. LTF also protects against infections and inflammatory complications, caused by diagnostic surgical interventions in pregnant women. Beneficial, multidirectional actions of LTF during pregnancy encompass, in addition, inhibition of oxidative stress, normalization of intestine and genital tract microbiota and carbohydrate-lipid metabolism, protection of intestine barrier function, promotion of wound healing, as well as hypotensive, analgesic and antistress actions. Bovine lactoferrin (BLTF) is readily available on the nutritional market and generally recognized as safe (GRAS) for use in human diet.

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.

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.

Integrated bioinformatics analysis reveals novel key biomarkers and potential candidate small molecule drugs in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is the metabolic disorder that appears during pregnancy. The current investigation aimed to identify central differentially expressed genes (DEGs) in GDM. The transcription profiling by array data (E-MTAB-6418) was obtained from the ArrayExpress database. The DEGs between GDM samples and non-GDM samples were analyzed. Functional enrichment analysis were performed using ToppGene. Then we constructed the protein–protein interaction (PPI) network of DEGs by the Search Tool for the Retrieval of Interacting Genes database (STRING) and module analysis was performed. Subsequently, we constructed the miRNA–hub gene network and TF–hub gene regulatory network. The validation of hub genes was performed through receiver operating characteristic curve (ROC). Finally, the candidate small molecules as potential drugs to treat GDM were predicted by using molecular docking. Through transcription profiling by array data, a total of 869 DEGs were detected including 439 up-regulated and 430 down-regulated genes. Functional enrichment analysis showed these DEGs were mainly enriched in reproduction, cell adhesion, cell surface interactions at the vascular wall and extracellular matrix organization. Ten genes, HSP90AA1, EGFR, RPS13, RBX1, PAK1, FYN, ABL1, SMAD3, STAT3 and PRKCA were associated with GDM, according to ROC analysis. Finally, the most significant small molecules were predicted based on molecular docking. This investigation identified hub genes, signal pathways and therapeutic agents, which might help us, enhance our understanding of the mechanisms of GDM and find some novel therapeutic agents for GDM.

Iron, iodine and vitamin D deficiencies during pregnancy: epidemiology, risk factors and developmental impacts

Micronutrient deficiency persists throughout the world, and although the burden is higher in low-resource settings, it is also prevalent in wealthy countries, a phenomenon termed 'hidden hunger'. Due to their high requirements for vitamins and minerals relative to their energy intake, young women and children are particularly vulnerable to hidden hunger. As they share several risk factors and impact on overlapping outcomes, we consider how deficiency of iron, iodine and vitamin D can have profound impacts on perinatal health and infant development. We review the epidemiology of these micronutrient deficiencies during pregnancy, including social, environmental and dietary risk factors. We identify the main challenges in defining nutritional status of these nutrients using validated diagnostic criteria linked with meaningful clinical outcomes. Public health strategies are urgently required to improve the overall health and nutritional status of women of reproductive age. Obesity prevention and early detection of malnutrition with standardised screening methods would detect pregnant women at increased risk of iron deficiency. Development of sensitive, individual biomarkers of iodine status is required to protect maternal health and fetal/infant brain development. Risk assessments of vitamin D requirements during pregnancy need to be revisited from the perspective of fetal and neonatal requirements. International consensus on standardised approaches to micronutrient assessment, analysis and reporting as well as sensitive, clinically validated infant and child neuro-behavioural outcomes will enable progression of useful observational and intervention studies.

Are Pregnant Women Who Are Living with Overweight or Obesity at Greater Risk of Developing Iron Deficiency/Anaemia?

Low-grade inflammation is often present in people living with obesity. Inflammation can impact iron uptake and metabolism through elevation of hepcidin levels. Obesity is a major public health issue globally, with pregnant women often affected by the condition. Maternal obesity is associated with increased pregnancy risks including iron deficiency (ID) and iron-deficiency anaemia (IDA)-conditions already highly prevalent in pregnant women and their newborns. This comprehensive review assesses whether the inflammatory state induced by obesity could contribute to an increased incidence of ID/IDA in pregnant women and their children. We discuss the challenges in accurate measurement of iron status in the presence of inflammation, and available iron repletion strategies and their effectiveness in pregnant women living with obesity. We suggest that pre-pregnancy obesity and overweight/obese pregnancies carry a greater risk of ID/IDA for the mother during pregnancy and postpartum period, as well as for the baby. We propose iron status and weight gain during pregnancy should be monitored more closely in women who are living with overweight or obesity.

Effect of Maternal Nutritional Status and Mode of Delivery on Zinc and Iron Stores at Birth

Zinc and iron deficiencies among infants aged under 6 months may be related with nutrient store at birth. This study aimed to investigate the association between zinc and iron stores at birth with maternal nutritional status and intakes during pregnancy. 117 pregnant women were enrolled at the end of second trimester and followed until delivery. Clinical data during pregnancy, including pre-pregnancy body mass index (BMI) and at parturition were collected from medical record. Zinc and iron intakes were estimated from a food frequency questionnaire. Serum zinc and ferritin were determined in maternal blood at enrollment and cord blood. Mean cord blood zinc and ferritin were 10.8 ± 2.6 µmol/L and 176 ± 75.6 µg/L, respectively. Cord blood zinc was associated with pre-pregnancy BMI (adj. ß 0.150; p = 0.023) and serum zinc (adj. ß 0.115; p = 0.023). Cord blood ferritin was associated with pre-pregnancy BMI (adj. ß -5.231; p = 0.009). Cord blood zinc and ferritin were significantly higher among those having vaginal delivery compared to cesarean delivery (adj. ß 1.376; p = 0.007 and 32.959; p = 0.028, respectively). Maternal nutritional status and mode of delivery were significantly associated with zinc and iron stores at birth. Nutrition during preconception and pregnancy should be ensured to build adequate stores of nutrients for infants.

Systemic inflammatory status - a bridge between gestational weight gain and neonatal outcomes (STROBE-compliant article)

Pregnant women with excessive gestational weight gain express an inflammatory status with multiple negative effects on birth outcomes.The aim of this study was to identify the relationship between gestational weight gain at different gestational ages and inflammatory status in pregnant women and their newborns assessing both interleukin 6 and 8, as well as hepcidin in these couples.Our study included 170 pregnant women and their newborns. Pregnant women were clinically assessed at the end of the 1st trimester and at term, whereas the newborns were assessed over the first 3 days of life. The levels of interleukin 6, 8 and hepcidin were measured in both pregnant women and their newborns.We noticed higher levels of interleukin 6, interleukin 8 and hepcidin in pregnant women at the time of delivery as compared to the end of the 1st trimester. We observed a direct significant correlation between gestational weight gain at the time of delivery and interleukin 8 in both mothers [r = 0.1834, 95% CI: 0.0293-0.3290, (P = .0167)] and newborns [r = 0.1790, 95% CI: 0.0248-0.3249, (P = .0195)]. Our study underlined that a higher gestational weight gain resulted in a significantly higher birth weight [r = 0.2190, 95% CI: 0.0663-0.3617, (P = .0041)].Our findings suggest that interleukin 8 might be an important indicator of inflammatory status in both mothers and newborns. Moreover, excessive gestational weight gain was associated with an increase in birth weight.

Maternal hepcidin determines embryo iron homeostasis in mice

Iron disorders are associated with adverse pregnancy outcomes, yet iron homeostatic mechanisms during pregnancy are poorly understood. In humans and rodents, the iron-regulatory hormone hepcidin is profoundly decreased in pregnant mothers, which is thought to ensure adequate iron availability for transfer across placenta. However, the fetal liver also produces hepcidin, which may regulate fetal iron endowment by controlling placental iron export. To determine the relative contribution of maternal vs embryo hepcidin to the control of embryo iron endowment in iron-sufficient or iron-overloaded mice, we generated combinations of mothers and embryos that had or lacked hepcidin. We found that maternal, but not embryonic, hepcidin determined embryo and placental iron endowment in a healthy pregnancy. We further determined that inflammation can counteract pregnancy-dependent suppression of maternal hepcidin. To establish how essential maternal hepcidin suppression is for embryo iron homeostasis, we mimicked the range of maternal hepcidin activity by administering a hepcidin peptide mimetic to pregnant mice. This also allowed us to determine the effect of isolated maternal hepcidin excess on pregnancy, in the absence of other confounding effects of inflammation. Higher doses of hepcidin agonist caused maternal iron restriction and anemia, lower placenta and embryo weight, embryo anemia, and increased embryo mortality. Low agonist doses did not cause maternal anemia but still adversely affected the embryo, causing anemia, tissue iron deficiency (including in the brain), and decreased weight. Our studies demonstrate that suppression of maternal hepcidin during pregnancy is essential for maternal and embryo iron homeostasis and health.

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.

Placental distribution of endogenous and exogenous substances: A pilot study utilizing cryo-sampled specimen off delivery room

INTRODUCTION

Reliability in the use of placentome (including placenta, umbilical cord, and cord blood) biomarkers requires an understanding of their distributions. Here we aim to develop a simple and proper placenta sampling scheme, and to evaluate the placental distributions of biomarkers.

METHODS

We developed a continuous cooling chain protocol off delivery room and cryo-subsampling method for placenta sampling. The levels of thyroid hormones (THs), elements, persistent organic pollutants (POPs), monoamines, and vitamin E were measured using UPLC-Q-TOF-MS, HPLC-ICP-MS, HPLC-EcD, and HRGC-HRMS, respectively. The distributions of biomarkers were assessed.

RESULTS

In human placentome, _l-thyroxine (T₄), Cd, Se, Zn, Cu, Fe, Ca, K, Mg, α-tocopherol, β-tocopherol, and β-tocotrienol levels were higher in placenta than in umbilical cord, while Pb and Mn were concentrated in human cord. In porcine placentome, T₄, 3,3',5'-triiodo-_l-thyronine (rT₃), 3,3'-diiodo-_l-thyronine, Cd, Pb, Zn, K, and Al levels were higher in the cord. The intraclass correlation coefficient (ICC) was <0.4 for 3,3',5-triiodo-_l-thyronine, rT₃, α-tocopherol, and 7 elements in human basal plate, indicating low reliability. rT₃, Cd, Zn, Mn, and Cu were significantly concentrated in the central region in human placenta, while higher levels of As, Cd, Cr, and Al were found in the periphery region in porcine placenta. Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) showed moderate reliability (ICC: 0.40-0.98) except PCB-81, -126, and BDE-208, while polychlorinated dibenzo-p-doixins/furans (PCDD/Fs) showed poor reliability (ICC: 0.07-0.31).

DISCUSSION

These results highlight the complexity of placenta sampling. This study provides a novel and simple sampling approach in investigating placental exposomics.

Modification of the effects of prenatal manganese exposure on child neurodevelopment by maternal anemia and iron deficiency

BACKGROUND

We evaluated: (1) associations of prenatal manganese (Mn) levels with child neurodevelopment at 4-6 years; (2) effect modification by maternal anemia and iron deficiency; and (3) sex-specific effects.

METHODS

We measured blood Mn, hemoglobin, and serum ferritin in mothers at the second trimester, third trimester, and at birth, and in cord blood from a prospective birth cohort in Mexico City (n = 571). McCarthy Scales of Children's Abilities were measured at 4-6 years. Using linear regression, we estimated associations between prenatal Mn and neurodevelopment, examined anemia and iron deficiency as effect modifiers, and analyzed associations by child sex.

RESULTS

No direct associations were observed between Mn, anemia, or iron deficiency and McCarthy Scales. Second trimester iron deficiency and third trimester anemia modified the effect of Mn on child neurodevelopment. For instance, second trimester Mn was positively associated child memory scores in mother's with normal ferritin (1.85 (0.02, 3.45)), but negatively associated in mother's with low ferritin (-2.41 (-5.28, 0.47), interaction P value = 0.01), a pattern observed across scales. No effect modification at birth or in cord blood was observed.

CONCLUSIONS

Anemia/iron deficiency during pregnancy may modify Mn impacts on child neurodevelopment, particularly in boys.

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.

Prepregnancy Obesity Is Not Associated with Iron Utilization during the Third Trimester

BACKGROUND

An adequate maternal iron supply is crucial for maternal red blood cell (RBC) expansion, placental and fetal growth, and fetal brain development. Obese women may be at risk for poor iron status in pregnancy due to proinflammatory-driven overexpression of hepcidin leading to decreased iron bioavailability.

OBJECTIVE

The objective of this study was to determine the impact of prepregnancy (PP) obesity on third-trimester maternal iron utilization.

DESIGN

Using the stable isotope 57Fe, we measured iron utilization in the third trimester in PP obese [BMI (in kg/m2): ≥30] and nonobese (BMI: 18.5-29.9) women. We also assessed iron status, hepcidin, inflammation, erythropoietin, dietary iron intake, and gestational weight gain. Descriptive and inferential statistical tests (e.g., Student t test, Pearson correlation) were used for data analysis.

RESULTS

Fifty pregnant women (21 PP obese, 29 PP nonobese) were included. Mean age was 27.6 ± 6.8 y and mean gestational age at time of 57Fe administration was 32.7 ± 0.7 wk. Anemia (hemoglobin <11 g/dL for non-black and <10.2 g/dL for black women) affected 38% of women (43% PP obese compared with 35% PP nonobese; P = 0.55). Women with PP obesity had significantly higher C-reactive protein (8.5 compared with 3.4 mg/L, P = 0.0007) and total body iron corrected for inflammation (6.0 compared with 4.3 mg/kg, P = 0.04) compared with the nonobese women. There was no difference in serum hepcidin or iron utilization between the PP BMI groups.

CONCLUSION

This is the first study to assess the impact of PP obesity on maternal iron utilization. We found no difference in iron utilization in the third trimester of pregnancy in women with and without PP obesity. Despite higher frequency of anemia, women with PP obesity had less depleted body iron stores, suggesting some degree of iron sequestration. This finding should be followed up and extended to understand effects on fetal iron bioavailability.

Association of maternal BMI during early pregnancy with infant anemia: a large Chinese birth cohort

BACKGROUND

Infant anemia is prevalent in low- and middle-income countries. Maternal body mass index (BMI) is associated with serum ferritin in cord blood, but as yet has not been linked to infant anemia. The objective of this study was to examine the association of maternal BMI during early pregnancy with infant hemoglobin levels and anemia at 6 and 12 months in a Chinese birth cohort.

METHODS

The prospective cohort included 17,193 mother-infant pairs. Maternal weight and height prior to 20 gestational weeks as well as infant hemoglobin at 6 and 12 months were measured following standard procedures, and BMI was calculated as weight in kilograms divided by the square of height in meters. Women were categorized into underweight, normal weight (reference), overweight, and obesity. Infant anemia was defined as hemoglobin < 11.0 g/dl. Fractional polynomial regression was used to examine the relation between maternal BMI and infant hemoglobin, joinpoint regression to identify breakpoints, and logistic regression to estimate odds ratios (ORs).

RESULTS

In the cohort, 1160 (6.8%) were anemic at 6 months and 904 (5.3%) at 12 months. An inverse U-shaped relation of maternal BMI with infant hemoglobin was found at 6 months, at their maximum at maternal BMI of 22.4 kg/m2, and a similar relationship found again at 12 months. Maternal obesity rather than underweight was associated with an increased risk of anemia for infants at 6 months (adjusted OR 1.39, 95% CI 1.02, 1.88), but not at 12 months. Maternal anemia during mid-pregnancy augmented the risk at 6 months (adjusted OR 2.91, 95% CI 1.14, 7.46), but did not mediate the association (Z = - 1.102, P = 0.270).

CONCLUSIONS

Maternal BMI during early pregnancy is correlated with infant hemoglobin in an inverse U-shaped profile, and obesity increases infant anemia risk that is aggravated by maternal anemia during pregnancy. This study enriched the epidemiological evidence on the adverse effect of high maternal BMI on long-term health of offspring. Optimizing maternal weight in obstetric care is necessary to improve offspring health.

Serum hepcidin and iron status parameters in pregnant women and the association with adverse maternal and fetal outcomes: a study protocol for a prospective cohort study

INTRODUCTION

Hepcidin production is normally upregulated by iron stores, and in obesity has been shown to be overexpressed and correlated with low iron status. The increased hepcidin may restrain the iron release from the cells by affecting the expression of ferroportin, which probably associates with the development of diabetes complication. First, we investigate the difference of serum hepcidin and iron parameters between obese and non-obese pregnant women; second, we examine the correlation between serum hepcidin and adverse maternal and neonatal outcomes in pregnant women.

METHODS AND ANALYSIS

This is a mono-centre, prospective cohort study with a study (obese) and a control group (non-obese women). In the first trimester, 188 singleton pregnancies will be recruited. Thereof, we expect 75 with a body mass index (BMI) ≥30 kg/m2 and 113 with a BMI 18.5-30 kg/m2. Serum hepcidin, iron and haematological parameters will be measured at 11-14, 24-28, 32-36 weeks of gestation and at time of delivery. Blood pressure, weight, BMI and smoking status will be examined at all visits. We will assess the composite endpoints adverse maternal outcomes (including pre-eclampsia, gestational hypertension, gestational diabetes mellitus, haemorrhage, placenta abruption) and adverse neonatal outcomes (preterm birth, intrauterine growth restriction, preterm premature rupture of membranes, Apgar score <7 at 5 min, stillbirth, neonatal death).Recruitment has started in April 2019.

ETHICS AND DISSEMINATION

This study received ethical approval from the ethics committee in Basel. The results of the study will be published in a peer-reviewed journal, and presented at national scientific conferences.

TRIAL REGISTRATION NUMBER

NCT03792464.

Obesity Is Associated with Changes in Iron Nutrition Status and Its Homeostatic Regulation in Pregnancy

The influence of obesity on maternal iron homeostasis and nutrition status during pregnancy remains only partially clarified. Our study objectives were (1) to describe how obesity influences broad iron nutrition spectrum biomarkers such as available or circulating iron (serum transferrin receptor (sTfr) and serum iron), iron reserves (ferritin), and functional iron (hemoglobin); and (2) to depict the regulating role of hepcidin. The above was carried out while considering influential factors such as initial iron nutrition status, iron intake, and the presence of inflammation. Ninety three non-anemic pregnant adult women were included, 40 with obesity (Ob) and 53 with adequate weight (AW); all took ≈30 mg/day of supplementary iron. Information on iron intake and blood samples were obtained at gestational weeks 13, 20, 27, and 35. A series of repeated measure analyses were performed using General Linear Models to discern the effect of obesity on each iron indicator; iron intake, hepcidin, and C-reactive protein were successively introduced as covariates. Available and circulating iron was lower in obese women: sTfr was higher (p = 0.07) and serum iron was lower (p = 0.01); and ferritin and hemoglobin were not different between groups. Hepcidin was higher in the Ob group (p = 0.01) and was a significant predictor variable for all biomarkers. Obesity during pregnancy dysregulates iron homeostasis, resembling "obesity hypoferremia".

The effect of maternal iron deficiency on zinc and copper levels and on genes of zinc and copper metabolism during pregnancy in the rat

Fe deficiency is relatively common in pregnancy and has both short- and long-term consequences. However, little is known about the effect on the metabolism of other micronutrients. A total of fifty-four female rats were fed control (50 mg Fe/kg) or Fe-deficient diets (7·5 mg/kg) before and during pregnancy. Maternal liver, placenta and fetal liver were collected at day 21 of pregnancy for Cu and Zn analysis and to measure expression of the major genes of Cu and Zn metabolism. Cu levels increased in the maternal liver (P=0·002) and placenta (P=0·018) of Fe-deficient rats. Zn increased (P&lt;0·0001) and Cu decreased (P=0·006) in the fetal liver. Hepatic expression of the Cu chaperones antioxidant 1 Cu chaperone (P=0·042) and cytochrome c oxidase Cu chaperone (COX17, P=0·020) decreased in the Fe-deficient dams, while the expression of the genes of Zn metabolism was unaltered. In the placenta, Fe deficiency reduced the expression of the chaperone for superoxide dismutase 1, Cu chaperone for superoxide dismutase (P=0·030), ceruloplasmin (P=0·042) and Zn transport genes, ZRT/IRT-like protein 4 (ZIP4, P=0·047) and Zn transporter 1 (ZnT1, P=0·012). In fetal liver, Fe deficiency increased COX17 (P=0·020), ZRT/IRT-like protein 14 (P=0·036) and ZnT1 (P=0·0003) and decreased ZIP4 (P=0·004). The results demonstrate that Fe deficiency during pregnancy has opposite effects on Cu and Zn levels in the fetal liver. This may, in turn, alter metabolism of these nutrients, with consequences for development in the fetus and the neonate.

The Impact of Maternal Pre-Pregnancy Body Weight and Gestational Diabetes on Markers of Folate Metabolism in the Placenta

Dietary methyl donors, including folate, may modify the placenta and size at birth but the influence of maternal body weight has not been widely investigated. We therefore examined whether maternal or fetal folate status, together with indices of placental folate transport, were modulated by either maternal pre-pregnancy body mass index (BMI i.e., overweight: 25 ≤ BMI < 30 or obesity: BMI ≥ 30 kg/m²) and/or gestational diabetes mellitus (GD). We utilised a sub-sample of 135 pregnant women participating in the Spanish PREOBE survey for our analysis (i.e., 59 healthy normal weight, 29 overweight, 22 obese and 25 GD). They were blood sampled at 34 weeks gestation, and, at delivery, when a placental sample was taken together with maternal and cord blood. Placental gene expression of folate transporters and DNA methyltransferases (DNMT) were all measured. Folate plasma concentrations were determined with an electro-chemiluminescence immunoassay. Food diaries indicated that folate intake was unaffected by BMI or GD and, although all women maintained normal folate concentrations (i.e., 5–16 ng/mL), higher BMIs were associated with reduced maternal folate concentrations at delivery. Umbilical cord folate was not different, reflecting an increased concentration gradient between the mother and her fetus. Placental mRNA abundance for the folate receptor alpha (FOLR1) was reduced with obesity, whilst DNMT1 was increased with raised BMI, responses that were unaffected by GD. Multi-regression analysis to determine the best predictors for placental FOLR1 indicated that pre-gestational BMI had the greatest influence. In conclusion, the placenta’s capacity to maintain fetal folate supply was not compromised by either obesity or GD.

Relationships between Maternal Obesity and Maternal and Neonatal Iron Status

Obesity in pregnancy may negatively influence maternal and infant iron status. The aim of this study was to examine the association of obesity with inflammatory and iron status in both mother and infant in two prospective studies in pregnancy: UPBEAT and SCOPE. Maternal blood samples from obese (n = 245, BMI ≥ 30 kg/m²) and normal weight (n = 245, BMI < 25 kg/m²) age matched pregnant women collected at approximately 15 weeks’ gestation, and umbilical cord blood samples collected at delivery, were analysed for a range of inflammatory and iron status biomarkers. Concentrations of C- reactive protein and Interleukin-6 in obese women compared to normal weight women were indicative of an inflammatory response. Soluble transferrin receptor (sTfR) concentration [18.37 nmol/L (SD 5.65) vs. 13.15 nmol/L (SD 2.33)] and the ratio of sTfR and serum ferritin [1.03 (SD 0.56) vs. 0.69 (SD 0.23)] were significantly higher in obese women compared to normal weight women (P < 0.001). Women from ethnic minority groups (n = 64) had higher sTfR concentration compared with white women. There was no difference in maternal hepcidin between obese and normal weight women. Iron status determined by cord ferritin was not statistically different in neonates born to obese women compared with neonates born to normal weight women when adjusted for potential confounding variables. Obesity is negatively associated with markers of maternal iron status, with ethnic minority women having poorer iron statuses than white women.

Association between pre-pregnancy weight status and maternal micronutrient status in early pregnancy

OBJECTIVE

Inadequate maternal micronutrient status during pregnancy can lead to short- and long-term health risks for mother and offspring. The present study investigated the association between pre-pregnancy weight status and micronutrient status during pregnancy.

DESIGN

Maternal blood samples were collected during early pregnancy (median 13, interquartile range 12-15 weeks) and were assayed for serum folate, ferritin, Fe and vitamin B12. Regression modelling was used to assess the association between pre-pregnancy underweight, normal weight, overweight and obesity, and micronutrient levels, as well as the odds for deficiencies.

SETTING

The Amsterdam Born Children and their Development (ABCD) study, the Netherlands.

SUBJECTS

Women with singleton pregnancies without diabetes (n 4243).

RESULTS

After adjustment for covariates, overweight women and obese women had lower (β; 95 % CI) folate (-1·2; -2·2, -0·2 and -2·3; -4·0, -0·7 nmol/l, respectively) and Fe (-1·7; -2·3, -1·1 and -3·6; -4·7, -2·6 μmol/l, respectively) levels than women with normal weight. Furthermore, overweight women had 6 % (95 % CI -9, -3 %) and obese women had 15 % (-19, -10 %), lower vitamin B12 levels, and obese women had 19 % (6, 32 %) higher ferritin levels, than normal-weight women. Obese women had higher odds (OR; 95 % CI) for folate deficiency (2·03; 1·35, 3·06), Fe deficiency (3·26; 2·09, 5·08) and vitamin B12 deficiency (2·05; 1·41, 2·99) than women with normal weight. Underweight was not associated with micronutrient status.

CONCLUSIONS

During early pregnancy, women with pre-pregnancy overweight and obesity had lower serum folate, Fe and vitamin B12 status. This resulted in increased risk of serum folate, Fe and vitamin B12 deficiencies in women with obesity.

Iron status of North American pregnant women: an update on longitudinal data and gaps in knowledge from the United States and Canada

Pregnant women are particularly vulnerable to iron deficiency due to the high iron demands of pregnancy. To avoid the adverse birth outcomes that are associated with maternal iron deficiency anemia, both Canada and the United States recommend universal iron supplementation for pregnant women. Although the benefits of iron supplementation in anemic women are well recognized, insufficient data are currently available on the maternal and neonatal benefits and harms of universal iron supplementation in developed countries as evidenced by the recent conclusions of the US Preventive Services Task Force on the need for further data that address existing gaps. As part of an effort to evaluate the impact of the current North American prenatal iron supplementation policy, this review highlights the lack of national data on longitudinal changes in iron status in pregnant North American women, emphasizes possible limitations with the original longitudinal hemoglobin data used to inform the current CDC reference hemoglobin values, and presents additional normative data from recent longitudinal research studies of iron status in North American pregnant women. Further longitudinal data in North American pregnant women are needed to help identify those who may benefit most from supplementation as well as to help determine whether there are adverse effects of iron supplementation in iron-replete women.

Longitudinal Analysis of the Interaction Between Obesity and Pregnancy on Iron Homeostasis: Role of Hepcidin

BACKGROUND AND AIMS

When pregnancy occurs in obese women, two opposite mechanisms for iron homeostasis concur: increased need for available iron to support erythropoiesis and decreased iron mobilization from diets and stores due to obesity-related inflammation linked to overexpressed hepcidin. Few studies have examined the role of hepcidin on maternal iron homeostasis in the context of obese pregnancy. The aim of the study was to evaluate the combined effect of maternal obesity and pregnancy on hepcidin and maternal iron status while accounting for inflammation and iron supplementation.

METHODS

We conducted a secondary analysis of a cohort of pregnant women recruited from a referral obstetric hospital in Mexico City. Circulating biomarkers of iron status (hepcidin, ferritin [SF], transferrin receptor [sTfR], erythropoietin [EPO]), and inflammation (C-reactive protein [CRP], tumor necrosis factor-[TNF]α, and interleukin-[IL]6) were determined monthly throughout pregnancy. Repeated measures ANOVA and logistic regression models were used for statistics.

RESULTS

Twenty-three obese (Ob) and 25 lean (Lc) women were studied. SF and hepcidin declined, and EPO and sTfR increased throughout pregnancy in both groups. sTfR increased more in Ob than in Lc (p = 0.024). The smallest hepcidin decline occurred in iron-supplemented Ob women compared to non-supplemented Lc women (p = 0.022). The risk for iron deficiency at the end of pregnancy was higher for Ob than for Lc (OR = 4.45, 95% CI = 2.07-9.58) after adjusting for iron supplementation and hepcidin concentration.

CONCLUSION

Pre-gestational obesity increases the risk of maternal iron deficiency despite iron supplementation. Overexpressed hepcidin appears to be a potential mechanism.

Mitochondrial content and hepcidin are increased in obese pregnant mothers

OBJECTIVE

Maternal obesity is characterized by systemic low-grade inflammation and oxidative stress (OxS) with the contribution of fetal sex dimorphism. We recently described increased mitochondrial content (mtDNA) in placentas of obese pregnancies. Here, we quantify mtDNA and hepcidin as indexes of OxS and systemic inflammation in the obese maternal circulation.

METHODS

Forty-one pregnant women were enrolled at elective cesarean section: 16 were normal weight (NW) and 25 were obese (OB). Obese women were further classified according to the presence/absence of maternal gestational diabetes mellitus (GDM); [OB/GDM(-)]: n = 15, [OB/GDM(+)]: n = 10. mtDNA and hepcidin were evaluated in blood (real-time PCR) and plasma (ELISA).

RESULTS

mtDNA and hepcidin levels were significantly increased in OB/GDM(-) versus NW, significantly correlating with pregestational BMI. Male/female (M/F) ratio was equal in study groups, and overall F-carrying pregnancies showed significantly higher mtDNA and hepcidin levels than M-carrying pregnancies both in obese and normal weight mothers.

CONCLUSIONS

Our results indicate a potential compensatory mechanism to increased obesity-related OxS and inflammation, indicated by the higher hepcidin levels found in obese mothers. Increased placental mitochondrial biogenesis, due to lipotoxic environment, may account for the greater mtDNA amount released in maternal circulation. This increase is namely related to F-carrying pregnancies, suggesting a gender-specific placental response.

Increased birth weight is associated with altered gene expression in neonatal foreskin

Elevated birth weight is linked to glucose intolerance and obesity health-related complications later in life. No studies have examined if infant birth weight is associated with gene expression markers of obesity and inflammation in a tissue that comes directly from the infant following birth. We evaluated the association between birth weight and gene expression on fetal programming of obesity. Foreskin samples were collected following circumcision, and gene expression analyzed comparing the 15% greatest birth weight infants (n=7) v. the remainder of the cohort (n=40). Multivariate linear regression models were fit to relate expression levels on differentially expressed genes to birth weight group with adjustment for variables selected from a list of maternal and infant characteristics. Glucose transporter type 4 (GLUT4), insulin receptor substrate 2 (IRS2), leptin receptor (LEPR), lipoprotein lipase (LPL), low-density lipoprotein receptor-related protein 1 (LRP1), matrix metalloproteinase 2 (MMP2), plasminogen activator inhibitor-1 (PAI-1) and transcription factor 7-like 2 (TCF7L2) were significantly upregulated and histone deacetylase 1 (HDAC1) and thioredoxin (TXN) downregulated in the larger birth weight neonates v.

CONTROLS

Multivariate modeling revealed that the estimated adjusted birth weight group difference exceeded one standard deviation of the expression level for eight of the 10 genes. Between 25 and 50% of variation in expression level was explained by multivariate modeling for eight of the 10 genes. Gene expression related to glycemic control, appetite/energy balance, obesity and inflammation were altered in tissue from babies with elevated birth weight, and these genes may provide important information regarding fetal programming in macrosomic babies.

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

Impact of maternal, antenatal and birth-associated factors on iron stores at birth: data from a prospective maternal-infant birth cohort

BACKGROUND/OBJECTIVES

Low serum ferritin concentrations at birth, which reflect neonatal iron stores, track through to early childhood and have been associated with poorer neurodevelopmental outcomes. We aimed to identify maternal, antenatal and birth-associated factors that influence iron stores at birth in a prospective maternal-infant birth cohort.

SUBJECTS/METHODS

In a population-based, longitudinal, birth cohort in Ireland, 413 maternal-infant dyads with prospectively collected lifestyle and clinical data from 15 weeks' gestation had umbilical cord serum ferritin concentrations measured. Regression models were developed to identify independent factors associated with cord ferritin concentrations.

RESULTS

Median (IQR) cord ferritin concentrations were 185.7 (131.7, 385.5) μg/l, and 8% (n=33) of infants had low iron stores (ferritin <76 μg/l) at birth. Maternal obesity (BMI ⩾30 kg/m²) at 15 weeks' gestation (adj. estimate (95% confidence interval (CI)): -66.4 (-106.9, -25.9) μg/l, P<0.0001) and delivery by caesarean section (-38.8 (-70.2, -7.4) μg/l, P=0.016) were inversely associated with cord ferritin concentrations. In addition, maternal smoking at 15 weeks' gestation (adj. odds ratio (95% CI): 2.9 (1.2, 7), P=0.020) and being born small-for-gestational age (3.4 (1.3, 8.9), P=0.012) were associated with an increased risk of low iron stores (ferritin <76 μg/l) at birth.

CONCLUSIONS

We have identified a number of potentially modifiable lifestyle factors that influence iron stores at birth, with the important role of overall maternal health and lifestyle during pregnancy highlighted. Public health policies targeting women of child-bearing age to improve nutrition and health outcomes should be prioritised for the health of the next generation.

Iron Metabolism in African American Women in the Second and Third Trimesters of High-Risk Pregnancies

OBJECTIVE

To examine iron metabolism during the second and third trimesters in African American women with high-risk pregnancies.

DESIGN

Longitudinal pilot study.

SETTING

Large, university-based, urban Midwestern U.S. medical center.

PARTICIPANTS

Convenience sample of 32 African American women with high-risk pregnancies seeking care at an urban maternal-fetal medicine clinic.

METHODS

Nonfasting venous blood was collected in the second and third trimesters to assess iron status, hepcidin, and systemic inflammation. Anthropometric and survey data were obtained via self-report. Descriptive statistics were calculated from these data, and changes in the clinical parameters between the second and third trimesters were evaluated via paired t tests. Associations among demographic, reproductive, anthropometric, inflammatory, and iron-related parameters were also assessed in each trimester.

RESULTS

The mean age of participants was 28.3 (± 6.8) years, and mean prepregnancy body mass index was 31.9 (± 10.7) kg/m². In the longitudinal analysis, significant (p < .05) declines in serum iron, ferritin, transferrin saturation, and C-reactive protein were observed between the second and third trimesters. There was no statistically significant change in hepcidin between trimesters. When using a ferritin level cut-point of less than 15 ng/ml and soluble transferrin receptor level of greater than 28.1 nmol/L, 48% of the participants (14 of 29) were classified with iron deficiency in the third trimester.

CONCLUSION

In this pilot study, iron deficiency was prevalent among a small cohort of African American women with high-risk pregnancies. Hepcidin concentrations were greater than previously reported in healthy, pregnant, primarily White women, which suggests decreased iron bioavailability in this high-risk group.

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.

Supplementation during pregnancy: beliefs and science

Pregnancy represents a challenge from a nutritional perspective, because micronutrient intake during the periconceptional period and in pregnancy affects fetal organ development and the mother's health. Inappropriate diet/nutrition in pregnancy can lead to numerous deficiencies including iron deficiency and may impair placental function and play a role in miscarriage, intrauterine growth restriction, preterm delivery, and preeclampsia. This article reviews the risks associated with nutrient deficiencies in pregnant women and presents an overview of recommendations for dietary supplementation in pregnancy, focusing on oral iron supplementation. Risk factor detection, including dietary patterns and comorbidities, is paramount in optimal pregnancy management. Dietary habits, which can lead to deficiencies (e.g., iron, folate, vitamin D, and calcium) and result in negative health consequences for the mother and fetus/newborn, need to be investigated. Prenatal care should be personalized, accounting for ethnicity, culture, education, information level about pregnancy, and dietary and physical habits. Clinicians should make a plan for appropriate supplementation and prophylaxis/treatment of nutritional and other needs, and consider adequate intake of calcium, iodine, vitamin D, folate, and iron. Among the available oral iron supplements, prolonged-released ferrous sulfate (ferrous sulfate-polymeric complex) presents the lowest incidence of overall and gastrointestinal adverse events, with positive implications for compliance.

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.

Does Body Mass Index in Pregnant Women Affect Laboratory Parameters in the Newborn?

Objective The objective of this study was to determine the effect of body mass index (BMI) during pregnancy in laboratory parameters in the serum of the three groups of pregnant women and in their newborns. Methods This prospective study is comparison between the three groups of pregnant women and their newborns categorized according to their BMI. The study included 128 pregnant women and their newborns. In this study, the concentration of blood count, iron, ferritin, and bilirubin were analyzed in the subjects. Results The pregnant women in the three groups significantly differ in the values of blood count (p < 0.001). Statistically significant difference in iron and ferritin was not found between individual three studied groups of pregnant women (p = 0.947). The newborn of the first group of pregnant women had significantly lower values of ferritin (p < 0.001), leucocytes (p < 0.001), and bilirubin (p < 0.001). Significant positive correlation between BMI of pregnant women and leucocytes, ferritin, and bilirubin of the newborn was found (p < 0.001). Conclusion In this study, the tested pregnant women do not have biochemical signs of anemia, neither do their newborns. It was noted that there was no negative correlation between individual tested biochemical parameters for anemia in pregnant women and their newborns.

Maternal, fetal and perinatal alterations associated with obesity, overweight and gestational diabetes: an observational cohort study (PREOBE)

Background

Maternal overweight, obesity, and gestational diabetes (GD) have been negatively associated with offspring development. Further knowledge regarding metabolic and nutritional alterations in these mother and their offspring are warranted.

Methods

In an observational cohort study we included 331 pregnant women from Granada, Spain. The mothers were categorized into four groups according to BMI and their GD status; overweight (n:56), obese (n:64), GD (n:79), and healthy normal weight controls (n:132). We assessed maternal growth and nutritional biomarkers at 24 weeks (n = 269), 34 weeks (n = 310) and at delivery (n = 310) and the perinatal characteristics including cord blood biomarkers.

Results

Obese and GD mothers had significantly lower weight gain during pregnancy and infant birth weight, waist circumference, and placental weight were higher in the obese group, including a significantly increased prevalence of macrosomia. Except for differences in markers of glucose metabolism (glucose, HbA1c, insulin and uric acid) we found at some measures that overweight and/or obese mothers had lower levels of transferrin saturation, hemoglobin, Vitamin B12 and folate and higher levels of C-reactive protein, erythrocyte sedimentation rate, ferritin, and cortisol. GD mothers had similar differences in hemoglobin and C-reactive protein but higher levels of folate. The latter was seen also in cord blood.

Conclusions

We identified several metabolic alterations in overweight, obese and GD mothers compared to controls. Together with the observed differences in infant anthropometrics, these may be important biomarkers in future research regarding the programming of health and disease in children.

Trial registration

The trial was registered at clinicaltrials.gov, identifier (NCT01634464).

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.