Maternal inflammation at delivery affects assessment of maternal iron status

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.

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

Background

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

Methods

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

Results

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

Conclusion

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

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

OBJECTIVE

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

DATA SOURCES

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

STUDY ELIGIBILITY CRITERIA

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

METHODS

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

RESULTS

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

CONCLUSION

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

Placental Erythroferrone and Erythropoietin mRNA Expression is not Associated with Maternal or Neonatal Iron Status in Adolescents Carrying Singletons and Adult Women Carrying Multiples

BACKGROUND

The iron regulatory hormones erythroferrone (ERFE), erythropoietin (EPO), and hepcidin, and the cargo receptor nuclear receptor coactivator 4 (NCOA4) are expressed in the placenta. However, determinants of placental expression of these proteins and their associations with maternal or neonatal iron status are unknown.

OBJECTIVES

To characterize expression of placental ERFE, EPO, and NCOA4 mRNA in placentae from newborns at increased risk of iron deficiency and to evaluate these in relation to maternal and neonatal iron status and regulatory hormones.

METHODS

Placentae were collected from 114 neonates born to adolescents carrying singletons (14-18 y) and 110 neonates born to 54 adults (20-46 y) carrying multiples. Placental EPO, ERFE, and NCOA4 mRNA expression were measured by RT-qPCR and compared with maternal and neonatal iron status indicators (SF, sTfR, total body iron, serum iron) and hormones.

RESULTS

Placental ERFE, EPO, and NCOA4 mRNA were detected in all placentae delivered between 25 and 42 wk of gestation. Relationships between placental ERFE and EPO differed by cohort. In the multiples cohort, placental EPO and ERFE were positively correlated (P = 0.004), but only a positive trend (P = 0.08) was evident in the adolescents. Placental EPO and ERFE were not associated with maternal or neonatal iron status markers or hormones in either cohort. Placental NCOA4 was not associated with placental EPO or ERFE in either cohort but was negatively associated with maternal SF (P = 0.03) in the multiples cohort and positively associated with neonatal sTfR (P = 0.009) in the adolescents.

CONCLUSIONS

The human placenta expresses ERFE, EPO, and NCOA4 mRNA as early as 25 wk of gestation. Placental expression of ERFE and EPO transcripts was not associated with maternal or neonatal iron status. Greater placental NCOA4 transcript expression was evident in women and newborns with poor iron status (lower SF and higher sTfR, respectively). Further research is needed to characterize the roles of these proteins in the human placenta.

TRIAL REGISTRATION NUMBER

These clinical trials were registered at clinicaltrials.gov as NCT01019902 (https://clinicaltrials.gov/ct2/show/NCT01019902) and NCT01582802 (https://clinicaltrials.gov/ct2/show/NCT01582802).

Iron-Deficiency Prevalence and Supplementation Practices Among Pregnant Women: A Secondary Data Analysis From a Clinical Trial in Vancouver, Canada

BACKGROUND

North American public health guidelines recommend supplementation with an iron-containing prenatal multivitamin throughout pregnancy to meet the RDA of 27 mg of elemental iron daily. However, whether supplementation with standard prenatal multivitamins is sufficient to prevent maternal iron deficiency is unclear, as needs increase substantially with advancing gestation.

OBJECTIVES

This study aimed to assess iron status in early and late pregnancy among 60 pregnant women receiving 27 mg/day of elemental iron as part of a randomized trial in Vancouver, Canada.

METHODS

Study visits were conducted at 8-21 (baseline) and 24-38 (endline) weeks of gestation. Venous blood specimens were collected for a complete blood count and measurement of iron and inflammatory biomarkers. Supplementation with any additional iron (beyond 27 mg/day) was reported by participants (treatment with additional iron is recommended if ferritin is <30 μg/L). Quantile regression was used to explore predictors of endline ferritin concentrations, including ethnicity, education, income, and baseline ferritin measurement.

RESULTS

Overall, 60 and 54 women participated in baseline and endline visits, respectively. Rates of probable iron deficiency (ferritin <30 μg/L) at baseline and endline were 17 (28%) and 44 (81%), respectively. Less than half (n = 18; 41%) of participants with probable iron deficiency at endline reported supplementation with additional iron. Ethnicity was the only significant modifier of endline ferritin, with higher concentrations in those of South, East, and Southeast Asian ethnicity compared to those of European ethnicity (β: 10.4 μg/L; 95% CI: 0.3-20.5).

CONCLUSIONS

Pregnant individuals may require additional supplemental iron beyond 27 mg to meet requirements in later pregnancy, given the high rates of iron deficiency observed in this clinical trial, despite consumption meeting 100% of the RDA. This trial was registered at clinicaltrials.gov as NCT04022135.

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.

Iron status of full-term infants in early infancy is not associated with maternal ferritin levels nor infant feeding practice

Iron deficiency (ID) in early life is associated with morbidities. Most fetal iron required for infant growth is acquired in the third trimester from maternal iron store. However, how prenatal iron level affects ferritin level in early infancy remains controversial. This study aimed to examine the associations between maternal ferritin levels and cord blood serum ferritin (CBSF) and to compare the ferritin levels between different feeding practices in early infancy. Healthy Chinese mothers with uncomplicated pregnancy and their infants were followed up at 3 months post-delivery for questionnaire completion and infant blood collection. Infants who were predominantly breastfed and those who were predominantly formula fed were included in this analysis. Serum ferritin levels were measured in maternal blood samples collected upon delivery, cord blood and infant blood samples at 3 months of age. Ninety-seven mother-baby dyads were included. Maternal ID is common (56 %) while the CBSF levels were significantly higher than maternal ferritin levels. Only three infants (3 %) had ID at 3 months of age. There were no significant correlations between maternal ferritin levels with CBSF (r 0·168, P = 0·108) nor with infant ferritin levels at 3 months of age (r 0·023, P = 0·828). Infant ferritin levels at 3 months were significantly and independently associated with CBSF (P = 0·007) and birth weight (P < 0·001) after adjusting for maternal age, parity, maternal education, infant sex and feeding practice. In conclusion, maternal ID was common upon delivery. However, maternal ferritin levels were not significantly associated with CBSF concentrations nor infant ferritin concentrations at 3 months of age.

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.

Serum Erythroferrone During Pregnancy Is Related to Erythropoietin but Does Not Predict the Risk of Anemia

BACKGROUND

Maintaining adequate iron status during pregnancy is important for the mother and her developing fetus. Iron homeostasis is influenced by 3 regulatory hormones: erythropoietin (EPO), hepcidin, and erythroferrone (ERFE). To date, normative data on ERFE across pregnancy and its relations to other hormones and iron status indicators are limited.

OBJECTIVES

The objective of this study was to characterize maternal ERFE across pregnancy and at delivery and evaluate the utility of hepcidin, ERFE, and EPO in identifying women with increased iron needs.

METHODS

ERFE was measured in extant serum samples collected from 2 longitudinal cohorts composed of women carrying multiple fetuses (n = 79) and pregnant adolescents (n = 218) at midgestation (∼26 wk) and delivery (∼39 wk). Receiver operating characteristic curves were generated to characterize the predictive ability of serum ERFE, hepcidin, and EPO and their ratios to identify women at increased risk of iron deficiency and anemia.

RESULTS

In these pregnant women, mean ERFE was 0.48 ng/mL at both ∼25 wk of gestation and at delivery. ERFE was positively associated with EPO at midgestation (β = 0.14, P = 0.002, n = 202) and delivery (β = 0.12, P < 0.001, n = 225) but was not significantly associated with maternal hepcidin at any time point surveyed. Of all hormones measured at midgestation and delivery, EPO was best able to identify women with anemia (AUC: 0.86 and 0.75, respectively) and depleted iron stores (AUC: 0.77 and 0.84), whereas the hepcidin-to-EPO ratio was best able to identify women with iron deficiency anemia (AUC: 0.85 and 0.84).

CONCLUSIONS

Maternal ERFE was significantly associated with EPO but was not able to identify women with gestational iron deficiency. At term, the hepcidin-to-EPO ratio, an index that accounts for both iron status and erythropoietic demand, and EPO were the strongest indicators of maternal iron deficiency and anemia. This trial was registered at clinicaltrials.gov as NCT04517734 (https://clinicaltrials.gov/ct2/show/NCT04517734).

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.

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.

Intravenous iron isomaltoside versus oral iron supplementation for treatment of iron deficiency in pregnancy: protocol for a randomised, comparative, open-label trial

BACKGROUND

Iron deficiency is common in pregnancy. If left untreated, iron deficiency can lead to iron deficiency anaemia, which is a condition related to maternal and neonatal morbidity. The prevalence of iron deficiency increases through the trimesters, which means that women with iron deficiency in the beginning of pregnancy also have a great risk of developing iron deficiency anaemia during pregnancy. Standard treatment is oral iron in individualised intensified doses based on screening values in 1st trimester. Maternal symptoms of iron deficiency and iron deficiency anaemia include fatigue, reduced physical performance, and restless legs syndrome (RLS). Severe anaemia may cause dizziness, dyspnea, palpitation, orthostatism, and syncope, and it decreases the woman's ability to cope with blood loss during delivery. The anaemia may also compromise contractility in the uterine musculature increasing the risk for prolonged labour, caesarean section, and postpartum haemorrhage. Foetal iron deficiency may cause low birthweight and adversely affect foetal and early childhood brain development with long-term deficits.

METHODS

In this randomised comparative, open-label, single-centre, phase IV trial, 200 pregnant women between 14 and 21 weeks of gestation who have iron deficiency after 4 weeks of standard treatment will be randomised 1:1 to either a single 1000 mg dose of intravenously administered ferric derisomaltose/iron isomaltoside 1000 or a fixed dose of 100 mg oral ferrous fumarate containing 60 mg ascorbic acid. The primary endpoint is to prevent iron deficiency anaemia defined by a low level of haemoglobin throughout the trial. Other endpoints include other haematological indices of iron deficiency and anaemia, clinical outcomes by questionnaires, and collection of adverse events. Explorative endpoints by medical record follow-up include complications up to 7 days after delivery.

DISCUSSION

This trial will provide evidence on how to prevent iron deficiency anaemia. The trial population represents a clinical reality where pregnant women often have sustained iron deficiency despite an increased oral iron dose. Thus, this evidence can be used to consider the optimal 2nd line of treatment in iron-deficient pregnant women.

TRIAL REGISTRATION

European Union Drug Regulating Authorities Clinical Trials Database 2017-000776-29. Registered on 3 May 2017. ClinicalTrials.gov NCT03188445 . Registered on 15 June 2017.

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".

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Vitamin B12 Status in Pregnant Adolescents and Their Infants

Vitamin B₁₂ deficiency has been associated with increased risk of adverse pregnancy outcomes. Few prospective studies have investigated the burden or determinants of vitamin B₁₂ deficiency early in life, particularly among pregnant adolescents and their children. The objectives of this study were to determine the prevalence of vitamin B₁₂ deficiency and to examine associations between maternal and neonatal vitamin B₁₂ status in a cohort study of healthy pregnant adolescents. Serum vitamin B₁₂ and folate concentrations were measured in adolescents at mid-gestation (n = 124; 26.4 ± 3.5 weeks) and delivery (n = 131; 40.0 ± 1.3 weeks), and in neonates at birth using cord blood. Linear regression was used to examine associations between maternal and neonatal vitamin B₁₂ status. Although the prevalence of vitamin B₁₂ deficiency (<148.0 pmol/L; 1.6%) in adolescents was low during pregnancy, 22.6% of adolescents were vitamin B₁₂ insufficient (<221.0 pmol/L; 22.6%) at mid-gestation. Maternal vitamin B₁₂ concentrations significantly decreased from mid-gestation to delivery (p < 0.0001), and 53.4% had insufficient vitamin B₁₂ status at delivery. Maternal vitamin B₁₂ concentrations (p < 0.001) and vitamin B₁₂ deficiency (p = 0.002) at delivery were significantly associated with infant vitamin B₁₂ concentrations in multivariate analyses, adjusting for gestational age, maternal age, parity, smoking status, relationship status, prenatal supplement use, pre-pregnancy body mass index, race, and intake of vitamin B₁₂ and folate. Maternal vitamin B₁₂ concentrations significantly decreased during pregnancy and predicted neonatal vitamin B₁₂ status in a cohort of healthy pregnant adolescents.

Patterns and Correlates of Self-Reported Physical Activity in a Cohort of Racially Diverse Pregnant Adolescents

STUDY OBJECTIVE

Regular physical activity (PA) during pregnancy decreases the risk of gestational hypertension and preeclampsia. Currently, little is known about the PA of pregnant adolescents. Our intent was to characterize the PA behaviors of a group of racially diverse, low-income pregnant teens and to identify potential determinants of PA.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTIONS

A cohort of 157 racially diverse pregnant adolescents (13-18 years of age) completed up to 3 previous day PA recalls as part of a larger prospective longitudinal study on determinants of maternal and fetal bone health. Subjects self-reported activities from 7 AM to 11:30 PM, choosing from a list of 37 activities including a category for "other." Subjects recorded activities in 30-minute intervals.

MAIN OUTCOME MEASURES

Estimated metabolic equivalent task (MET) values were assigned to each activity and summed for a measure of total daily PA in MET min/d. Determinants of PA were evaluated using a stepwise linear mixed effect model.

RESULTS

The average calculated MET min/d was 1478 ± 130. Significant determinants of MET min/d included race (P = .007), maternal age at conception (P = .042), gestational age (P = .002), and attending school (P < .001). Black teens were less physically active than white teens, and older teens were more active than younger teens; activity decreased throughout gestation, and teens currently attending school were more active.

CONCLUSION

PA is low across gestation and pregnant teens spent more than half of their monitored time in sedentary activities. Targeted interventions are needed to achieve current PA goals in this pediatric obstetric population.

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.

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.

Low Vitamin D is Associated With Infections and Proinflammatory Cytokines During Pregnancy

Vitamin D is known to regulate innate and adaptive immune processes at the cellular level, but the role of vitamin D status on associated inflammatory processes across pregnancy is unclear. Our primary objective was to evaluate the relationships between serum biomarkers of inflammation (interleukin [IL]-6, IL-10, tumor necrosis factor [TNF]-α), acute-phase proteins (C-reactive protein and hepcidin) and vitamin D status, 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)₂D), measured across pregnancy and in the neonate at birth. A second objective was to identify associations between vitamin D status and clinically diagnosed infections. In this study, 158 racially and ethnically diverse pregnant adolescents were recruited from the Rochester Adolescent Maternity Program (RAMP) in Rochester, NY. Serum 1,25(OH)₂D was significantly lower in adolescents and neonates with IL-6 concentrations above the 75th percentile at delivery ( P = .04) and at birth ( P = .004), respectively. After adjusting for other potential covariates of inflammation, maternal serum 1,25(OH)₂D was significantly positively associated with TNF-α during pregnancy ( P = .02), but at delivery 1,25(OH)₂D and TNF-α were inversely associated with one another ( P = .02). Teens with 25(OH)D concentrations <30 ng/mL were more likely to test positive for candida ( P = .002) and bacterial vaginosis ( P = .02) during pregnancy. African Americans exhibited significantly lower TNF-α concentrations at both mid-gestation ( P = .009) and delivery ( P = .001) compared to the Caucasian adolescents. These results suggest that lower maternal vitamin D status may increase risk of infection across gestation.

Associations of Maternal Vitamin B12 Concentration in Pregnancy With the Risks of Preterm Birth and Low Birth Weight: A Systematic Review and Meta-Analysis of Individual Participant Data

Vitamin B12 (hereafter referred to as B12) deficiency in pregnancy is prevalent and has been associated with both lower birth weight (birth weight <2,500 g) and preterm birth (length of gestation <37 weeks). Nevertheless, current evidence is contradictory. We performed a systematic review and a meta-analysis of individual participant data to evaluate the associations of maternal serum or plasma B12 concentrations in pregnancy with offspring birth weight and length of gestation. Twenty-two eligible studies were identified (11,993 observations). Eighteen studies were included in the meta-analysis (11,216 observations). No linear association was observed between maternal B12 levels in pregnancy and birth weight, but B12 deficiency (<148 pmol/L) was associated with a higher risk of low birth weight in newborns (adjusted risk ratio = 1.15, 95% confidence interval (CI): 1.01, 1.31). There was a linear association between maternal levels of B12 and preterm birth (per each 1-standard-deviation increase in B12, adjusted risk ratio = 0.89, 95% CI: 0.82, 0.97). Accordingly, B12 deficiency was associated with a higher risk of preterm birth (adjusted risk ratio = 1.21, 95% CI: 0.99, 1.49). This finding supports the need for randomized controlled trials of vitamin B12 supplementation in pregnancy.

Early deterioration of iron status among a cohort of Bolivian infants

Iron deficiency (ID) and iron deficiency anemia (IDA) are major contributors to infant and maternal morbidity worldwide. There is limited longitudinal data on iron status in young infants and on methods to adjust iron biomarkers for inflammation. We aimed to quantify the prevalence of inflammation-adjusted ID, anemia, and IDA over the first year in a cohort of Bolivian infants and their mothers. Healthy mother-infant dyads were recruited from two peri-urban hospitals. Infants provided three blood draws (2, 6-8, and 12-18 months; N = 160); mothers provided two blood draws (1 and 6-8 months postpartum [plus third anemia measurement at 12-18 months]; N = 250). Blood was analyzed for hemoglobin, ferritin, soluble transferrin receptor, C-reactive protein (CRP), and alpha(1)-acid glycoprotein (AGP). Iron biomarkers were adjusted for inflammation using CRP and AGP; hemoglobin cutoffs were adjusted for altitude. Inflammation (elevated CRP or AGP) was 17% among toddlers 12-18 months of age. ID (inflammation-adjusted ferritin) increased with age (<1%, 56%, and 79% at each blood draw), as did anemia and IDA (anemia: 70%, 76%, and 81%; IDA: <1%, 46%, and 68%). Maternal ID declined from the first to second assessment (39% vs. 27%). Inflammation-adjusted ID prevalence was up to 15 percentage points higher than unadjusted estimates. The high prevalence of ID, anemia, and IDA in this cohort of Bolivian infants beginning at 6-8 months of age suggests that early interventions may be necessary in vulnerable populations.

Iron deficiency and anemia are prevalent in women with multiple gestations

BACKGROUND

Little attention has been placed on the unique iron demands that may exist in women with multiple gestations. This merits attention because iron deficiency (ID) during pregnancy is associated with adverse pregnancy outcomes that are known to be more prevalent in multiple births.

OBJECTIVE

We characterized longitudinal changes in iron status across pregnancy in a cohort of healthy women with multiple gestations and identified determinants of maternal ID and anemia.

DESIGN

A group of 83 women carrying twins, triplets, or quadruplets (aged 20-46 y) was recruited from 2011 to 2014. Blood samples obtained during pregnancy (∼24 wk; n = 73) and at delivery (∼35 wk; n = 61) were used to assess hemoglobin, serum ferritin (SF), soluble transferrin receptor (sTfR), hepcidin, serum iron, erythropoietin, serum folate, vitamin B-12, C-reactive protein, and interleukin-6.

RESULTS

The prevalence of tissue ID (sTfR >8.5 mg/L) increased significantly from pregnancy to delivery (9.6% compared with 23%, P = 0.03). Women with depleted iron stores (SF <12 μg/L, n = 20) during pregnancy had a 2-fold greater risk of anemia at delivery, and 25% (n = 5) developed iron deficiency anemia (IDA). Overall, 44.6% of women studied (n = 37/83) were anemic at delivery, and 18% of women (n = 11/61) had IDA. Erythropoietin during pregnancy was significantly negatively associated with hemoglobin at delivery. Women with erythropoietin >75th percentile during pregnancy exhibited a 3-fold greater risk of anemia, suggesting that erythropoietin is a sensitive predictor of anemia at delivery. Inflammation was present at delivery, which limited the utility of ferritin or hepcidin as iron-status indicators at delivery.

CONCLUSIONS

ID and anemia are highly prevalent in women with multiple gestations. Additional screening and iron supplementation may be warranted in this high-risk population given the known associations between ID anemia and adverse maternal and neonatal outcomes. This trial was registered at clinicaltrials.gov as NCT01582802.

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.

Maternal and Cord Blood Hepcidin Concentrations in Severe Iron Deficiency Anemia

BACKGROUND

The present study was conducted to assess the maternal and cord blood hepcidin concentrations in severe iron deficiency anemia (IDA) and to find out its correlation with other iron status parameters.

METHODS

This prospective observational study was carried out in 30 mothers with severe IDA (hemoglobin < 70 g/L and serum ferritin < 12 μg/L), and 15 healthy nonanemic (hemoglobin ≥ 110 g/L) mothers, who delivered live singleton neonates at term gestation. Mothers and neonates with infection/inflammatory conditions were excluded. Quantitative estimation of complete blood count, serum iron, ferritin, total iron binding capacity (TIBC), and transferrin saturation (Tfsat) was done in maternal and cord blood immediately after delivery by an auto analyzer. Serum hepcidin concentrations were measured by double-antibody sandwich enzyme-linked immunosorbent assay using a Human Hepcidin-25 kit. Data were analyzed by statistical software SPSS 16.0.

RESULTS

The serum iron and ferritin concentrations in severe IDA were 6.7 ± 1.8 μmol/L and 4.1 ± 1.4 μg/L in maternal blood, and 9.5 ± 2.6 μmol/L and 55.4 ± 19.7 μg/L in cord blood, respectively, significantly lower than nonanemic controls (p < 0.001). The corresponding serum hepcidin concentrations were 76.6 ± 22.7 μg/L and 110.5 ± 11.8 μg/L, respectively (p < 0.05). The proportion of cord blood/maternal blood hepcidin concentration was similar in both anemic (1.4:1) and nonanemic (1.3:1) mothers. Significant correlation was observed among maternal and cord blood hepcidin concentrations and other iron status parameters.

CONCLUSION

Even in the presence of low serum iron and ferritin, maternal and cord blood hepcidin concentrations remained high in severe anemia. Failure of this proportional suppression of hepcidin indicates poor systemic bioavailability of iron to the mother and poor placental transport.

Cross sectional, comparative study of serum erythropoietin, transferrin receptor, ferritin levels and other hematological indices in normal pregnancies and iron deficiency anemia during pregnancy

OBJECTIVE

To test the correlation of the serum erythropoietin levels, serum transferrrin receptor levels and serum ferritin levels along with other hematological parameters in normal pregnant and anemic pregnant patients.

STUDY DESIGN

In a prospective study, 120 pregnant women were recruited between 18 and 36 weeks of gestation; 53 normal pregnant patients, 67 anemic pregnant patients, in which, 17 had mild, 30 had moderate anemia, 20 had severe anemia. A blood sample was taken. The various hematological parameters, hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), total iron binding capacity (TIBC), serum ferritin, percentage saturation of iron, serum erythropoietin (SEPO) levels, serum transferrin receptors (STfRS) were performed. For statistics, Student's 't' test, Pearson's Chi test, Mann Whitney test and Bartlett test were used as per data.

RESULTS AND CONCLUSION

MCV was significantly reduced in anemic pregnancies as compared to non-anemic pregnancies (80.2±9.6 vs 94.12±9.8fl, p=0.001), MCHC was also reduced in them (30.2±3.38% vs 34.2±2.33%, p=0.176), TIBC was significantly increased in anemic pregnancies (343.31±28.54% vs 322.88±23.84%, p=0.001), serum ferritin was significantly reduced (24.9±10.48μg/L vs 31.03±9.98μg/L, p=0.001), percentage saturation of iron was also reduced (53.85±13.21% vs 62.04±15.79%, p=0.0024), serum erythropoietin levels were significantly higher in anemic women (26.24±26.61mU/ml vs 18.12±19.08mU/ml, p=0.064). The levels were significantly higher in severe anemia (46.5±46.8mU/ml than in moderate anemia 27.4±28.1mU/ml and mild anemia 22.8±22.8mU/ml. Serum transferrin receptors were significantly higher in anemic pregnancies than in non-anemic pregnancies (1.40±0.0802μg/ml vs 1.08±0.641μg/ml, p=0.019) with rise being higher in severe anemia (2.28±0.986μg/ml) than in moderate (1.4±0.816μg/ml) and mild anemia (1.16±0.702μg/ml).

CONCLUSION

Various hematological parameters especially sTfR, serum erythropoietin, serum ferritin and sTfR/log ferritin levels correlate with the severity of anemia.

Prevalence of anemia and associations between neonatal iron status, hepcidin, and maternal iron status among neonates born to pregnant adolescents

BACKGROUND

Little is known about anemia and iron status in US newborns because screening for anemia is typically not undertaken until 1 y of age. This study was undertaken to characterize and identify determinants of iron status in newborns born to pregnant adolescents.

METHODS

Pregnant adolescents (≤ 18 y, n = 193) were followed from ≥ 12 wk gestation until delivery. Hemoglobin, ferritin, soluble transferrin receptor, serum iron, hepcidin, erythropoietin (EPO), IL-6, and C-reactive protein were assessed in maternal and cord blood.

RESULTS

At birth, 21% of the neonates were anemic (Hb < 13.0 g/dl) and 25% had low iron stores (ferritin < 76 µg/l). Cord serum ferritin concentrations were not significantly associated with gestational age (GA) at birth across the range of 37-42 wk. Neonates born to mothers with ferritin < 12 µg/l had significantly lower ferritin (P = 0.003) compared to their counterparts. Hepcidin and IL-6 were significantly (P < 0.05) higher in neonates born to mothers with longer durations of active labor.

CONCLUSION

Given the importance of the iron stores at birth on maintenance of iron homeostasis over early infancy, additional screening of iron status at birth is warranted among those born to this high risk obstetric population.

Vitamin D status is inversely associated with anemia and serum erythropoietin during pregnancy

BACKGROUND

Vitamin D and iron deficiencies frequently co-exist. It is now appreciated that mechanistic interactions between iron and vitamin D metabolism may underlie these associations.

OBJECTIVE

We examined interrelations between iron and vitamin D status and their regulatory hormones in pregnant adolescents, who are a group at risk of both suboptimal vitamin D and suboptimal iron status.

DESIGN

The trial was a prospective longitudinal study of 158 pregnant adolescents (aged ≤18 y). Maternal circulating biomarkers of vitamin D and iron were determined at midgestation (∼25 wk) and delivery (∼40 wk). Linear regression was used to assess associations between vitamin D and iron status indicators. Bivariate and multivariate logistic regressions were used to generate the OR of anemia as a function of vitamin D status. A mediation analysis was performed to examine direct and indirect relations between vitamin D status, hemoglobin, and erythropoietin in maternal serum.

RESULTS

Maternal 25-hydroxyvitamin D [25(OH)D] was positively associated with maternal hemoglobin at both midgestation and at delivery (P < 0.01 for both). After adjustment for age at enrollment and race, the odds of anemia at delivery was 8 times greater in adolescents with delivery 25(OH)D concentrations <50 nmol/L than in those with 25(OH)D concentrations ≥50 nmol/L (P <0.001). Maternal 25(OH)D was inversely associated with erythropoietin at both midgestation (P <0.05) and delivery (P <0.001). The significant relation observed between 25(OH)D and hemoglobin could be explained by a direct relation between 25(OH)D and hemoglobin and an indirect relation that was mediated by erythropoietin.

CONCLUSIONS

In this group of pregnant adolescents, suboptimal vitamin D status was associated with increased risk of iron insufficiency and vice versa. These findings emphasize the need for screening for multiple nutrient deficiencies during pregnancy and greater attention to overlapping metabolic pathways when selecting prenatal supplementation regimens.

Antiretroviral Treatment Is Associated With Iron Deficiency in HIV-Infected Malawian Women That Is Mitigated With Supplementation, but Is Not Associated With Infant Iron Deficiency During 24 Weeks of Exclusive Breastfeeding

OBJECTIVE

In resource-limited settings without safe alternatives to breastfeeding, the WHO recommends exclusive breastfeeding and antiretroviral (ARV) prophylaxis. Given the high prevalence of anemia among HIV-infected women, mothers and their infants (through fetal iron accretion) may be at risk of iron deficiency. We assessed the effects of maternal micronutrient-fortified lipid-based nutrient supplements (LNS) and maternal ARV treatment or infant ARV prophylaxis on maternal and infant iron status during exclusive breastfeeding from birth to 24 weeks.

METHODS

The Breastfeeding, Antiretrovirals, and Nutrition study was a randomized controlled trial conducted in Lilongwe, Malawi, from 2004 to 2010. HIV-infected mothers (CD4 >200 cells/μL) and their infants were randomly assigned to 28-week interventions: maternal LNS/maternal ARV (n = 424), maternal LNS/infant ARV (n = 426), maternal LNS (n = 334), maternal ARV (n = 425), infant ARV (n = 426), or control (n = 334). Longitudinal models tested intervention effects on hemoglobin (Hb). In a subsample (n = 537) with multiple iron indicators, intervention effects on Hb, transferrin receptors (TfR), and ferritin were tested with linear and Poisson regression.

RESULTS

In longitudinal models, LNS effects on maternal and infant Hb were minimal. In subsample mothers, maternal ARVs were associated with tissue iron depletion (TfR >8.3 mg/L) (risk ratio: 3.1, P < 0.01), but not in ARV-treated mothers receiving LNS (P = 0.17). LNS without ARVs was not associated with iron deficiency or anemia (P > 0.1). In subsample infants, interventions were not associated with impaired iron status (all P > 0.1).

CONCLUSIONS

Maternal ARV treatment with protease inhibitors is associated with maternal tissue iron depletion; but LNS mitigates adverse effects. ARVs do not seem to influence infant iron status; however, extended use needs to be evaluated.

Prepregnancy Body Mass Index and Gestational Weight Gain Have No Negative Impact on Maternal or Neonatal Iron Status

OBJECTIVE

To assess the impact of maternal obesity and excessive gestational weight gain (GWG) on maternal and neonatal iron status and to explore the possible mediating role of inflammation on hepcidin.

METHODS

This analysis included 230 pregnant adolescents (13-18 years) enrolled in either a longitudinal or a cross-sectional study. Prepregnancy body mass index (ppBMI) and GWG were obtained from medical records. Maternal iron status (hemoglobin, serum iron, ferritin, transferrin receptor, total body iron, and hepcidin) and inflammation (interleukin-6 [IL-6] and leptin) were assessed at midgestation (26.2 ± 3.3 weeks) in the longitudinal cohort and at delivery (39.8 ± 1.3 weeks) in both study cohorts. Cord blood was collected in both studies and analyzed for iron indicators.

RESULTS

Approximately 40% of the adolescents entered pregnancy overweight or obese. Multivariate analysis identified ppBMI as a negative predictor of serum iron at midgestation (P = .009) and a positive predictor of serum hepcidin at delivery (P = .02). None of the other maternal iron status indicators were significantly associated with ppBMI or GWG. Serum IL-6 was significantly positively associated with hepcidin at delivery (P = .0001) but not at midgestation. There was a positive relationship between ppBMI and cord hemoglobin (P = .03).

CONCLUSION

These results suggest that adiposity-related inflammation does not override the iron-mediated signals that regulate hepcidin production during pregnancy, and in this adolescent cohort, there is no strong evidence for a detrimental effect of maternal obesity and excessive weight gain on iron status in the offspring at birth.

Gestational iron deficiency is associated with pica behaviors in adolescents

A relation between pica (the craving and purposive consumption of nonfood items) during pregnancy and anemia is observed frequently. However, few studies related pica behaviors to biomarkers of iron status, and little is known about pica prevalence in U.S. pregnant adolescents. To address this, we undertook a longitudinal study examining iron status and pica behaviors among a group of 158 pregnant adolescents (aged ≤18 y). Approximately two-thirds of the participants were African American and 25% were Hispanic. Maternal iron status indicators [hemoglobin, soluble transferrin receptor, serum ferritin (SF), total body iron (TBI), and serum hepcidin] were assessed during pregnancy (18.5-37.3 wk) and at delivery. Pica behavior was assessed up to 3 times across gestation. Among the 158 adolescents, 46% reported engaging in pica behavior. Substances ingested included ice (37%), starches (8%), powders (4%), and soap (3%). During pregnancy, mean SF [geometric mean: 13.6 μg/L (95% CI: 11.0, 17.0 μg/L)], TBI (mean ± SD: 2.5 ± 4.2 mg/kg), and hepcidin [geometric mean: 19.1 μg/L (95% CI: 16.3, 22.2 μg/L)] concentrations were significantly lower (P < 0.05) in the pica group (n = 72) than values observed among the non-pica group [SF, geometric mean: 21.1 μg/L (95% CI: 18.0, 25.0 μg/L); TBI, mean ± SD: 4.3 ± 3.5 mg/kg; hepcidin, geometric mean: 27.1 μg/L (95%: 23.1, 32.1 μg/L); n = 86]. Although additional studies must address the etiology of these relations, this practice should be screened for, given its association with low iron status and because many of the substances ingested may be harmful. This trial was registered at clinicaltrials.gov as NCT01019902.