Serum transferrin receptor: a specific marker of iron deficiency in pregnancy

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.

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 and Iron Deficiency Anemia in Women with and without Obesity: NHANES 2001-2006

Obesity has been linked to numerous health and nutritional problems, including impaired iron metabolism, a common cause of anemia. We aimed to determine the prevalence of anemia, iron deficiency (ID), and iron deficiency anemia (IDA) among women aged 20-49 years based on body mass index (BMI) status. We used measures of iron status and body mass index from the 2001-2006 National Health and Nutrition Examination Survey (NHANES). Mean serum ferritin, erythrocyte protoporphyrin, and soluble transferrin receptor were higher, while those of serum iron, percent transferrin saturation, and mean cell volume (MCV) were lower in women with obesity than those with normal weight (all p < 0.016). ID based on the ferritin model was 12.5 ± 1.0% vs. 22.9 ± 1.6% (p < 0.001); 9.0 ± 0.9% vs. 20.0 ± 1.3% (p < 0.001) based on the MCV model; and 8.1 ± 1.0% vs. 10.5 ± 1.2% (p > 0.05) based on the BII model for women with normal weight and women with obesity, respectively. Anemia prevalence was 5.5 ± 0.8% (normal) vs. 9.3 ± 1.0% (obese) (p = 0.005). The IDA estimates based on the ferritin and MCV models were similar but higher than that from the BII model (p < 0.001). Generally, the prevalence rates of ID and anemia (and IDA) were higher for women with obesity, but the method used to define deficiency mattered. The choice of iron indices is important for estimating ID and IDA in populations with obesity.

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 Deficiency Is a Risk Factor for Thyroid Dysfunction During Pregnancy: A Population-Based Study in Belgium

Background: Iron deficiency affects thyroid hormone synthesis by impairing the activity of the heme-dependent thyroid peroxidase. The prevalence of iron deficiency is elevated particularly in pregnant women. This study aimed to investigate the effects of iron status on thyroid function in a nationally representative sample of mildly iodine-deficient pregnant women. Methods: The study population comprised a sample of pregnant women in Belgium during the first and third trimesters of pregnancy (n = 1241). Women were selected according to a multistage proportional-to-size stratified and clustered sampling design. Urine and blood samples were collected, and a questionnaire was completed face to face with the study nurse. Concentrations of free thyroxine (fT4), total thyroxine (T4), free triiodothyronine, thyrotropin (TSH), thyroglobulin (Tg), thyroid peroxidase antibodies, Tg antibodies, hemoglobin, serum ferritin (SF), soluble transferrin receptor, urinary iodine concentrations (UICs) were measured and body iron stores (BIS) were calculated. Results: Median UICs were 117 and 132 μg/L in the first and third trimesters of pregnancy, respectively (p < 0.05). The frequency of SF <15 μg/L was 6.2% in the first trimester and 39.6% in the third trimester of pregnancy (p < 0.05). UIC was a significant predictor of serum Tg concentrations (p < 0.01) but not of thyroid hormone or TSH concentrations. The frequency of fT4<percentile 10th in the third trimester of pregnancy was 24% and 14% in pregnant women with negative BIS and positive BIS, respectively (p < 0.05). SF and BIS were significant predictors of fT4 and T4 in the first trimester of pregnancy (p < 0.05). Hemoglobin was a significant predictor of fT4 in both trimesters (p < 0.01) and for T4 in the third trimester (p = 0.015). Conclusion: Iron deficiency, but not mild iodine deficiency, is a determinant of serum fT4 and T4 in pregnant women. Correcting iron deficiency may help to maintain optimal thyroid function, in addition to preventing anemia during pregnancy.

Placental cadmium, placental genetic variations, and birth size

BACKGROUND

Maternal cadmium (Cd) burden has been associated with offspring birth size measures, yet associations of placental Cd with birth size are less clear. Further, the role of genetics in these associations has not been examined. We investigated associations of placental Cd with birth size and placental genotypes. We also examined the potential role of placental genotypes as modifiers of placental Cd and birth size associations.

METHODS

Participants were 490 mother-child pairs from the Omega and Placenta Microarray studies based in Seattle, WA. Placental Cd was measured using Agilent 7500 ICP-MS. The birth size was characterized using birth weight (BW), ponderal index (PI), and head circumference (HC). Eleven placental single nucleotide polymorphisms (SNPs) related to metal transport, growth regulation, endocrine response, and cell signaling were genotyped. Adjusted multivariable linear regression models were used to examine overall and sex-specific associations of placental Cd with birth size (BW, PI and HC), as well as associations of placental genotypes with placental Cd. Effect modification of placenta Cd and birth size associations by placental SNPs was examined using interaction terms and stratified analyses.

RESULTS

Mean maternal age was 33.6 years (SD = 4.4). Mean and median placental Cd levels were 4.0 ng/g tissue (SD = 2.7 ng/g tissue) and 3.6 ng/g (IQR 2.5 - 5.2 ng/g), respectively. Overall, compared with infants in the lowest quartile for placental Cd, infants in the second (ß = -102.8 g, 95% CI: -220.7, 15.1), third (ß = -83.2 g, 95% CI: -199.3, 32.9) and fourth (ß = -109.2 g, 95% CI: -225.4, 7.1) quartiles had lower BW, though associations were not statistically significant (all p-values > .05, trend p-value = .11). Among male infants, infants in the second (ß = -203.3 g, 95% CI: -379.7, -27.0) and fourth quartiles (ß = -198.3 g, 95% CI: -364.2, -32.5) had lower BW compared with those in the first quartiles (p-values < .05, trend p-value = .08). Similar relationships were not observed among female infants, though infant sex-placental Cd interaction terms were not significant. Similarly, male, but not female, infants had marginally significant positive associations between placental Cd and ponderal index (trend p-value = .06). The minor rs3811647 allele of the placental transferrin gene (NCBI Gene ID: 7018) was associated with an increase in Cd among all infants (p-value = .04). We did not find differences in associations of placental Cd with birth size markers among infants stratified by rs3811647 genotype.

CONCLUSIONS

Placental Cd was inversely associated with BW among male infants. The rs3811647 SNP of the transferrin gene was associated with placental Cd.

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).

First Trimester Ferritin Is Superior over Soluble Transferrin Receptor and Hepcidin in Predicting Anemia in the Third Trimester: Result from a Cohort Study in Indonesia

Introduction

Anemia in the third trimester has been identified as a risk factor for maternal and fetal morbidity that might lead to mortality. Due to its high cost, finding the best marker to predict anemia became more important to allow early prevention. Only one of ferritin, hepcidin, or soluble transferrin receptors can be picked for the prediction of anemia in the third trimester especially in low-resource setting.

Objective

This study aimed at defining the best marker among ferritin, hepcidin, or soluble transferrin receptor (sTfR) in the first trimester for prediction of anemia in the third trimester. Materials, Methods, and Setting. This diagnostic study was nested on the cohort study of vitamin D and its impact during pregnancy in Indonesia. Singleton pregnant mothers with normal fetus were recruited in the first trimester from four cities in West Java, Indonesia. The 304 pregnant women were screened for hepcidin, ferritin, and sTfR level in the sera. All biomarkers were measured by ELISA. Complete blood count (CBC) was done by impedance method measurement (Sysmex^R). Only subjects with complete data were included in analysis for diagnostic study to compare the three markers by finding the best receiver operating curve (RoC), likelihood ratio (LR), and risk estimate (RR).

Result

One-hundred and eighty-one pregnant women were eligible for analysis. The result of this study showed that the serum ferritin level in the first trimester was the best marker to predict anemia in the third trimester of pregnancy. Hepcidin and sTfR performed poorly. A new cutoff point of ferritin level ≤27.23 ng/ml yielded the best ROC with 67% area under curve (95% CI 60%-75%, p < 0.0001, Youden index J 0.28), specificity 86.29% (95% CI 79.0%-91.8%), LR (+) 3.07 (95% CI 1.8-5.3), and RR 2.48 (95% CI 1.67-3.68). These last figures were better than the previously used cutoff point of ferritin level below 30 ng/ml.

Conclusion

This study provided evidence that the serum ferritin level ≤27.23 ng/ml in the first trimester was the best marker to predict anemia in the third trimester. It was valuably useful for secondary screening of anemia in pregnancy, targeting subjects who may need rigorous approach for iron deficiency treatment in the prevention of anemia in pregnancy.

The Association of TMPRSS6 Gene Polymorphism and Iron Intake with Iron Status among Under-Two-Year-Old Children in Lombok, Indonesia

Multiple common variants in transmembrane protease serine 6 (TMPRSS6) were associated with the plasma iron concentration in genome-wide association studies, but their effect in young children where anemia and iron deficiency (ID) were prevalent has not been reported, particularly taking account of iron intake. This study aims to investigate whether TMPRSS6 SNPs (rs855791 and rs4820268) and iron intake are associated with a low iron and hemoglobin concentration in under-two-year-old children. The study analyzed the baseline of a randomized trial (NUPICO, ClinicalTrials.gov NCT01504633) in East Lombok, Indonesia. Children aged 6–17 months (n = 121) were included in this study. The multiple linear regressions showed that TMPRSS6 decreased serum ferritin (SF) by 4.50 g/L per copy minor allele (A) of rs855791 (p = 0.08) and by 5.00 μg/L per copy minor allele (G) of rs4820268 (p = 0.044). There were no associations between rs855791 and rs4820268 with soluble transferrin receptor (sTfR) and hemoglobin (Hb) concentration (rs855791; p = 0.38 and p = 0.13, rs4820268; p = 0.17 and p = 0.33). The finding suggests the need for further studies to explore whether the nutrient recommendation for iron should be based on genetic characteristics, particularly for children who have mutation in TMPRSS6.

Iron status at opposite ends of the menstrual function spectrum

OBJECTIVES

Although exercising women are at high risk of poor iron status, it is unknown how non-pathological, physiological menstrual function affects iron status. As such, this study investigates the association between menstrual function and iron status in exercising women with amenorrhea and exercising women with ovulatory, eumenorrheic menstrual cycles.

DESIGN

Cross-sectional analysis of iron depletion prevalence, iron status indices, exercise parameters, and diet composition.

METHODS

Women aged 18-35 years performing at least 2 h per week of aerobic exercise were recruited. Women with amenorrhea (AMEN) were defined by the absence of menses for at least 90 days or less than 6 menses in the past 12 months (n = 82). Women with ovulatory, eumenorrheic menstrual cycles (OvEU) were defined by the presence of ovulatory cycles of 26-35 days in length for the past 6 months (n = 109). Group differences in serum ferritin (Ft), soluble transferrin receptor (sTfR), total body iron (TBI), hemoglobin (Hb), hematocrit (Hct), iron depletion prevalence (Ft <15 μg/L), peak oxygen consumption (VO_2peak), exercise minutes per week, and diet logs were assessed.

RESULTS

The prevalence of iron depletion was greater in OvEU when compared to AMEN (26% vs. 15%, p = 0.04). No significant differences were observed between AMEN and OvEU in Ft (30.2 ± 2.2 vs. 24.9 ± 2.6 μg/L; p = 0.62), sTfR (5.2 ± 1.4 vs. 4.9 ± 1.5 mg/L; p = 0.95), TBI (5.3 ± 2.7 vs. 4.8 ± 3.7 mg/kg; p = 0.42), Hb (13.2 ± 0.4 vs. 13.4 ± 0.6 g/dL; p = 0.80), Hct (39.5 ± 0.8% vs. 39.8 ± 4.1%; p = 0.93), or exercise parameters. AMEN consumed more vitamin C than OvEU (269 ± 180 vs. 129 ± 141 mg/day, p < 0.001), but all other dietary factors were similar between AMEN and OvEU.

CONCLUSION

Exercising women with ovulatory, eumenorrheic cycles are at a greater risk of iron depletion than exercising, amenorrheic women. Thus, menstrual function must be considered when screening for poor iron status in exercising women.

Iron Deficiency May Predict Greater Risk for Hypothyroxinemia: A Retrospective Cohort Study of Pregnant Women in China

BACKGROUND

Pregnant women are highly vulnerable to iron deficiency (ID) due to the increased iron needs during pregnancy. ID decreases circulating thyroid hormone concentrations likely through impairment of iron-dependent thyroid peroxidase. The present study aimed to explore the association between ID and hypothyroxinemia in a retrospective cohort of pregnant women in China.

METHODS

To investigate the relationship between ID and hypothyroxinemia, 723 pregnant women were retrospectively analyzed, including 675 and 309 women in the second and third trimesters, respectively. Trimester-specific hypothyroxinemia was defined as free thyroxine (fT4) levels below the 2.5th percentile of the reference range with normal serum thyrotropin (TSH) or TSH higher than the 97.5th percentile of the reference range in each trimester of pregnancy. Serum TSH, fT4, thyroid peroxidase antibodies, thyroglobulin antibodies, serum ferritin, soluble transferrin receptor, and urinary iodine concentrations were measured. Serum ferritin, soluble transferrin receptor, and total body iron were used to indicate the nutritional iron status.

RESULTS

Cross-sectional multiple linear regression analysis showed that iron status was positively associated with serum fT4 levels in the first and second trimesters of pregnancy, but not in the third trimester. Logistic regression analysis showed that ID was an independent risk factor for hypothyroxinemia (odds ratio = 14.86 [confidence interval 2.31-95.81], p = 0.005 in the first trimester and odds ratio = 3.36 [confidence interval 1.01-11.21], p = 0.048 in the second trimester). The prospective analysis showed that pregnant women with ID during the first trimester of pregnancy had lower serum fT4 levels and a higher rate of hypothyroxinemia in the second or third trimester than those without ID.

CONCLUSIONS

ID appears to be a risk factor to predict hypothyroxinemia in the first and second trimesters of pregnancy, but not in the third trimester. Pregnant women with ID in the first and second trimesters should be regarded as a high-risk group for maternal hypothyroxinemia.

The reproductive ecology of iron in women

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

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.

The Homozygous Hemoglobin EE Genotype and Chronic Inflammation Are Associated with High Serum Ferritin and Soluble Transferrin Receptor Concentrations among Women in Rural Cambodia

BACKGROUND

Ferritin and soluble transferrin receptor (sTfR) concentrations are commonly used to assess iron deficiency (ID); however, they are influenced by multiple factors.

OBJECTIVES

We assessed associations between numerous variables and both ferritin and sTfR concentrations in Cambodian women and compared ID prevalence through the use of study-generated correction factors (CFs) for ferritin with those from a published meta-analysis.

METHODS

Venous blood from 450 women (aged 18-45 y) was assessed for hemoglobin (Hb), ferritin, sTfR, retinol binding protein, folate, vitamin B-12, C-reactive protein, α-1 acid glycoprotein (AGP), and genetic Hb disorders. Linear regression was used to calculate geometric mean ratios (95% CIs) for ferritin and sTfR concentrations.

RESULTS

The variant Hb EE genotype was associated with 50% (14%, 96%) and 51% (37%, 66%) higher geometric mean ferritin and sTfR concentrations, respectively, than was the normal Hb AA genotype; a 1-g/L increase in AGP was associated with 99% (50%, 162%) and 48% (33%, 64%) higher concentrations in the same variables, respectively. ID prevalence in nonpregnant women (n = 420) was 2% (n = 9) with the use of ferritin <15 μg/L and 18% (n = 79) with the use of sTfR >8.3 mg/L as criteria. ID prevalence with the use of sTfR was higher in women with the Hb EE genotype (n = 17; 55%) than in those with the Hb AA genotype (n = 20; 10%); and in women with the Hb AA genotype and chronic inflammation (n = 10; 18%) than in that group of women without chronic inflammation (n = 10; 7%) (P < 0.05). No differences in ID prevalence were found with the use of ferritin between women with Hb EE and AA genotypes (P = 1.0) or by chronic inflammation status (P = 0.32). There were no differences in mean ferritin concentrations among all 450 women when study-generated CFs were compared with those from the meta-analysis (P = 0.87).

CONCLUSIONS

Compared with sTfR, ferritin concentrations appear to reflect more accurately true ID in rural Cambodian women. The CFs from a published meta-analysis were appropriate for use in this population with a high prevalence of Hb disorders and inflammation.

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.

The effect of parity on maternal body mass index, plasma mineral element status and new-born anthropometrics

BACKGROUND

Adverse pregnancy outcome is an important public health problem that has been partly associated with increasing maternal parity.

AIM

To determine the effect of parity on maternal body mass index (BMI), mineral element status and newborn anthropometrics.

METHODS

Data for 349 pregnant women previously studied for the impacts of maternal plasma mineral element status on pregnancy and its outcomes was analysed. Obstetric and demographic data and 5mls of blood samples were obtained from each subject. Blood lead, plasma copper, iron and zinc were determined using atomic absorption spectrophotometer.

RESULTS

Maternal BMI increases with parity. Women with parity two had significantly higher plasma zinc but lower plasma copper with comparable levels of the elements in nulliparous and higher parity groups. Although plasma iron was comparable among the groups, blood lead was significantly higher in parity > three. Newborn birth length increases with parity with a positive correlation between parity and maternal BMI (r = 0.221; p = 0.001) and newborn birth length (r = 0.170; p = 0.002) while plasma copper was negatively correlated with newborn's head circumference (r = -0.115; p = 0.040).

CONCLUSION

It is plausible that parity affects maternal BMI and newborn anthropometrics through alterations in maternal plasma mineral element levels. While further studies are desired to confirm the present findings, there is need for pregnant and would-be pregnant women to diversify their diet to optimize their mineral element status.

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

BACKGROUND

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

OBJECTIVE

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

SUBJECTS/METHODS

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

RESULTS

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

CONCLUSIONS

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

Iron status and reproduction in US women: National Health and Nutrition Examination Survey, 1999-2006

Women experience significant changes in iron status throughout their reproductive lifespans. While this is evident in regions with high rates of malnutrition and infectious disease, the extent of reproductive-related changes is less well known in countries with low rates of iron deficiency anemia, such as the United States. The goal of this study is determine the relationship between women's reproductive variables (pregnancy, parity, currently breastfeeding, regular menstruation, hormonal contraceptive use, and age at menarche) and iron status (hemoglobin, ferritin, transferrin receptor, and % transferrin saturation) using an anthropological framework for interpreting the results. Data from women aged 18-49 were taken from the 1999-2006 US NHANES, a nationally representative cross-sectional sample of US women. Using multiple imputation and complex survey statistics, women's reproductive variables were regressed against indicators of iron status. Pregnant women had significantly poorer iron status, by most indicators, than non-pregnant women. All biomarkers demonstrated significantly lower iron levels with increasing parity. Women who were having regular periods had iron indicators that suggested decreased iron levels, while women who used hormonal contraceptives had iron indicators that suggested increased iron levels. Despite relatively good iron status and widespread availability of iron-rich foods in the US, women still exhibit patterns of iron depletion across several reproductive variables of interest. These results contribute to an ecological approach to iron status that seeks to understand variation in iron status, with the hopes that appropriate, population-specific recommendations can be developed to improve women's health.

Maternal inflammation at delivery affects assessment of maternal iron status

Pregnant adolescents (aged ≤ 18 y, n = 253) were followed from ≥ 12 wk of gestation to delivery to assess longitudinal changes in anemia and iron status and to explore associations between iron status indicators, hepcidin, and inflammatory markers. Hemoglobin, soluble transferrin receptor (sTfR), ferritin, serum iron, erythropoietin (EPO), hepcidin, C-reactive protein, interleukin-6 (IL-6), folate, and vitamin B-12 were measured, and total body iron (TBI) (milligrams per kilogram) was calculated using sTfR and ferritin values. Anemia prevalence increased from trimesters 1 and 2 (3-5%, <28 wk) to trimester 3 (25%, 33.2 ± 3.7 wk, P < 0.0001). The prevalence of iron deficiency (sTfR > 8.5 mg/L) doubled from pregnancy to delivery (7% to 14%, P = 0.04). Ferritin and hepcidin concentrations at delivery may have been elevated as a consequence of inflammation because IL-6 concentrations at delivery were 1.6-fold higher than those obtained at 26.1 ± 3.3 wk of gestation (P < 0.0001), and a positive association was found between IL-6 and both hepcidin and ferritin at delivery (P < 0.01). EPO was consistently correlated with hemoglobin (r = -0.36 and -0.43, P < 0.001), ferritin (r = -0.37 and -0.32, P < 0.0001), sTfR (r = 0.35 and 0.25, P < 0.001), TBI (r = -0.44 and -0.37, P < 0.0001), and serum iron (r = -0.22 and -0.16, P < 0.05) at mid-gestation and at delivery, respectively. EPO alone explained the largest proportion of variance in hemoglobin at 26.0 ± 3.3 wk of gestation (R(2) = 0.13, P = 0.0001, n = 113) and at delivery (R(2) = 0.19, P < 0.0001, n = 192). Pregnant adolescents are at high risk of anemia. EPO is a sensitive indicator of iron status across gestation, is not affected by systemic inflammation, and may better predict risk of anemia at term. The trial was registered at clinicaltrials.gov as NCT01019902.

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.

The aetiology of anaemia during pregnancy: a study to evaluate the contribution of iron deficiency and common infections in pregnant Ugandan women

Objective

To describe the aetiology of anaemia in pregnant Ugandan women and explore Fe deficiency and common infections as contributors to anaemia in this population.

Design

Cross-sectional study in which Hb, ferritin, transferrin receptor (sTfR), C-reactive protein, α-1 acid glycoprotein, hepcidin, malaria, hookworm infestation, syphilis and Helicobacter pylori infection were assessed.

Setting

Antenatal care clinic at Kawempe Health Centre, Kampala, Uganda.

Subjects

HIV-negative women (n 151) in their first or second pregnancy at 10–16 weeks’ gestation.

Results

The prevalence of anaemia was 29·1 %. Fe deficiency was 40·4 % and 14·6 % based on ferritin <30 μg/l and on adjusted ferritin <12 μg/l respectively, and 6·6 % based on sTfR >8·3 μg/ml. The prevalence of Fe-deficiency anaemia was 9·3 % based on ferritin <30 μg/l, 6·6 % based on adjusted ferritin <12 μg/l and 4·3 % based on sTfR >8·3 μg/ml. Hepcidin concentration was positively correlated with ferritin concentration (n 151, r=0·578, P<0·00001). H. pylori infection was highly prevalent (70 %) while malaria, hookworm infestation and syphilis were not common. Of all women, 60·3 % had α-1 acid glycoprotein >1 g/l and/or C-reactive protein >5 mg/l. Malaria parasitaemia (OR=6·85; 95 % CI 1·25, 37·41, P=0·026) and Fe deficiency defined using sTfR (OR=5·58; 95 % CI 1·26, 24·80, P=0·024) were independently and positively associated with anaemia. Population-attributable risk factors for anaemia for raised C-reactive protein, Fe deficiency defined by sTfR >8·3 μg/ml and presence of malaria parasites were 41·6 (95 % CI 11·1, 72·2) %, 13·5 (95 % CI 2·0, 25·0) % and 12·0 (95 % CI 1·4, 22·6) %, respectively.

Conclusions

Infections and inflammation are of greater significance than Fe deficiency in the aetiology of anaemia in pregnant Ugandan women during the first trimester.

Iron deficiency is associated with food insecurity in pregnant females in the United States: National Health and Nutrition Examination Survey 1999-2010

Food-insecure pregnant females may be at greater risk of iron deficiency (ID) because nutrition needs increase and more resources are needed to secure food during pregnancy. This may result in a higher risk of infant low birth weight and possibly cognitive impairment in the neonate. The relationships of food insecurity and poverty income ratio (PIR) with iron intake and ID among pregnant females in the United States were investigated using National Health and Nutrition Examination Survey 1999-2010 data (n=1,045). Food security status was classified using the US Food Security Survey Module. One 24-hour dietary recall and a 30-day supplement recall were used to assess iron intake. Ferritin, soluble transferrin receptor, or total body iron classified ID. Difference of supplement intake prevalence, difference in mean iron intake, and association of ID and food security status or PIR were assessed using χ(2) analysis, Student t test, and logistic regression analysis (adjusted for age, race, survey year, PIR/food security status, education, parity, trimester, smoking, C-reactive protein level, and health insurance coverage), respectively. Mean dietary iron intake was similar among groups. Mean supplemental and total iron intake were lower, whereas odds of ID, classified by ferritin status, were 2.90 times higher for food-insecure pregnant females compared with food-secure pregnant females. Other indicators of ID were not associated with food security status. PIR was not associated with iron intake or ID. Food insecurity status may be a better indicator compared with income status to identify populations at whom to direct interventions aimed at improving access and education regarding iron-rich foods and supplements.

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

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

Iron-containing micronutrient supplementation of Chinese women with no or mild anemia during pregnancy improved iron status but did not affect perinatal anemia

Universal prenatal daily iron-folic acid (IFA) and multiple micronutrient (MM) supplements are recommended to reduce the risk of low birth weight, maternal anemia, and iron deficiency (ID) during pregnancy, but the evidence of their effect on iron status among women with mild or no anemia is limited. The aim of this study was to describe the iron status [serum ferritin (SF), serum soluble transferrin receptor (sTfR), and body iron (BI)] before and after micronutrient supplementation during pregnancy. We examined 834 pregnant women with hemoglobin > 100 g/L at enrollment before 20 wk of gestation and with iron measurement data from a subset of a randomized, double-blind trial in China. Women were randomly assigned to take daily 400 μg of folic acid (FA) (control), FA plus 30 mg of iron, or FA, iron, plus 13 additional MMs provided before 20 wk of gestation to delivery. Venous blood was collected in this subset during study enrollment (before 20 wk of gestation) and 28-32 wk of gestation. We found that, at 28-32 wk of gestation, compared with the FA group, both the IFA and MM groups had significantly lower prevalence of ID regardless of which indicator (SF, sTfR, or BI) was used for defining ID. The prevalence of ID at 28-32 wk of gestation for IFA, MM, and FA were 35.3%, 42.7%, and 59.6% by using low SF, 53.6%, 59.9%, and 69.9% by using high sTfR, and 34.5%, 41.2%, and 59.6% by using low BI, respectively. However, there was no difference in anemia prevalence (hemoglobin < 110 g/L) between FA and IFA or MM groups. We concluded that, compared with FA alone, prenatal IFA and MM supplements provided to women with no or mild anemia improved iron status later during pregnancy but did not affect perinatal anemia. This trial was registered at clinicaltrials.gov as NCT00137744.

Polymorphisms in iron homeostasis genes and urinary cadmium concentrations among nonsmoking women in Argentina and Bangladesh

BACKGROUND

Cadmium (Cd) is a human toxicant and carcinogen. Genetic variation might affect long-term accumulation. Cd is absorbed via iron transporters.

OBJECTIVES

We evaluated the impact of iron homeostasis genes [divalent metal transporter 1 (SLC11A2), transferrin (TF), transferrin receptors (TFR2 and TFRC), and ferroportin (SLC40A1)] on Cd accumulation.

METHODS

Subjects were nonsmoking women living in the Argentinean Andes [n = 172; median urinary Cd (U-Cd) = 0.24 µg/L] and Bangladesh (n = 359; U-Cd = 0.54 µg/L) with Cd exposure mainly from food. Concentrations of U-Cd and Cd in whole blood or in erythrocytes (Ery-Cd) were measured by inductively coupled plasma mass spectrometry. Fifty polymorphisms were genotyped by Sequenom. Gene expression was measured in whole blood (n = 72) with Illumina DirectHyb HumanHT-12 v4.0.

RESULTS

TFRC rs3804141 was consistently associated with U-Cd. In the Andean women, mean U-Cd concentrations were 22% (95% CI: -2, 51%), and they were 56% (95% CI: 10, 120%) higher in women with GA and AA genotypes, respectively, relative to women with the GG genotype. In the Bangladeshi women, mean U-Cd concentrations were 22% (95% CI: 1, 48%), and they were 58% (95% CI: -3, 157%) higher in women with GA and AA versus GG genotype, respectively [adjusted for age and plasma ferritin in both groups; ptrend = 0.006 (Andes) and 0.009 (Bangladesh)]. TFRC expression in blood was negatively correlated with plasma ferritin (rS = -0.33, p = 0.006), and positively correlated with Ery-Cd (significant at ferritin concentrations of < 30 µg/L only, rS = 0.40, p = 0.046). Rs3804141 did not modify these associations or predict TFRC expression. Cd was not consistently associated with any of the other polymorphisms evaluated.

CONCLUSIONS

One TFRC polymorphism was associated with urine Cd concentration, a marker of Cd accumulation in the kidney, in two very different populations. The consistency of the findings supports the possibility of a causal association.

Plasma ferritin and soluble transferrin receptor concentrations and body iron stores identify similar risk factors for iron deficiency but result in different estimates of the national prevalence of iron deficiency and iron-deficiency anemia among women and children in Cameroon

Available iron status indicators reflect different aspects of metabolism. We compared the prevalence and distribution of iron deficiency (ID) and iron-deficiency anemia (IDA) among Cameroonian women and children, as measured by plasma ferritin, and soluble transferrin receptor concentrations, body iron stores (BIS), and hemoglobin, and evaluated the impact of adjustments for inflammation on these measures. In a nationally representative survey, we randomly selected 30 clusters in each of 3 zones (north, south, and large cities) and 10 households/ cluster, each with a child aged 12-59 mo and a woman 15-49 y. Ferritin and BIS were mathematically adjusted for inflammation, using plasma C-reactive protein and α(1)-acid glycoprotein both as continuous and categorical variables. Inflammation was present in 48.0% of children and 20.8% of women and anemia was diagnosed in 57.6% of children and 38.8% of women. Depending on the iron status indicator applied, the prevalence of ID ranged from 14.2 to 68.4% among children and 11.5 to 31.8% among women, and the prevalence of IDA ranged from 12.0 to 47.4% among children and 9.0 to 19.4% among women; the proportion of anemia associated with ID ranged from 20.8 to 82.3% among children and 23.2 to 50.0% among women. The different iron indicators generally identified similar groups at greatest risk of deficiency, using both conventional and derived cutoffs: younger children, pregnant women, and women and children in the north and rural areas. Research is needed to clarify the relationships between iron status indicators, particularly in the presence of inflammation, to harmonize global data on prevalence of ID.

Pregnancy and iron homeostasis: an update

It has been nearly 15 years since the first review on pregnancy and iron deficiency was published in Nutrition Reviews. Many unresolved issues raised in that seminal review have been addressed. New proteins involved in nonheme and heme iron transport have been identified in the enterocyte, and information on the roles of these proteins in the placenta is evolving. The systemic iron regulatory hormone, hepcidin, has since been identified as a key regulator of iron homeostasis. Additional data on the efficacy and consequences of prenatal iron supplementation are available. Emerging data on developmental changes in iron absorption across early infancy have further emphasized the need to ensure that the iron endowment of the neonate at birth is optimal. This is especially important, given growing evidence linking neonatal iron status with subsequent cognitive and neurobehavioral outcomes. Along with the many advances, new questions and gaps in knowledge have been identified. This review summarizes new data on maternal iron utilization across pregnancy as it impacts the pregnant woman and the iron status of the neonate at birth.

Iron status and its determinants in a nationally representative sample of pregnant women

Iron-deficiency anemia is associated with adverse neonatal health outcomes. Iron status and its determinants were assessed in a representative sample of Belgian pregnant women. Blood samples were collected and a questionnaire was completed face-to-face. Hemoglobin (Hb) and mean cell volume were measured using a Beckman Coulter Hematology Analyzer and serum ferritin (SF) and transferrin receptor (sTfr) concentrations by immunoassay. In total, 55 obstetric clinics and 1,311 pregnant women were included. Approximately 40% of third-trimester and 6% of first-trimester women had SF levels less than 15 μg/L. Approximately 21% of third-trimester and 4% of first-trimester women had anemia (Hb <110 g/L). Of the third-trimester women, 23% were iron-deficient nonanemic (SF <15 μg/L and Hb ≥110 g/L), 16% had iron-deficiency anemia (SF <15 μg/L and Hb <110 g/L), and approximately 7% had tissue iron deficiency (sTfr >8.5 mg/L). The median body iron stores were 8.1 mg/kg among first-trimester women, but only 3.6 mg/kg among third-trimester women. SF levels were significantly positively associated with age and education level, and were higher among nulliparous women and lower among North-African women. sTfr concentrations were significantly negatively associated with age and were lower among smokers, nulliparous women, and women who planned their pregnancy. Despite the fact that two thirds of Belgian pregnant women took iron-containing supplements, iron deficiency and iron-deficiency anemia were frequent in third-trimester women. The World Health Organization regards this as a moderate public health problem. National iron supplementation guidelines are needed in Belgium to optimize iron status during pregnancy.

Serum soluble transferrin receptor concentrations in US preschool children and non-pregnant women of childbearing age from the National Health and Nutrition Examination Survey 2003-2010

BACKGROUND

Serum soluble transferrin receptor (sTfR) is recommended as a sensitive and accurate measure of iron deficiency (ID) in populations when only a single indicator can be used. The lack of assay standardization and of representative data on the distribution of sTfR in at-risk populations currently limits its utility.

METHODS

Using data from NHANES 2003-2010, we examined the distribution of sTfR and developed assay-specific cutoff values for defining elevated sTfR in 2 US populations groups: children aged 1-5 y (n=2820) and non-pregnant women aged 15-49 y (n=6575).

RESULTS

On average, children had higher geometric mean sTfR concentrations (4.09 mg/l; 95% CI: 4.04-4.14) than non-pregnant women (3.31 mg/l; 95% CI: 3.26-3.35) (p<0.001). Among children, those aged 1-2 y (compared to those aged 3-5 y), boys (compared to girls), and non-Hispanic black (NHB) children (compared to non-Hispanic white (NHW) and Mexican-American (MA) children) had higher sTfR concentrations. Among non-pregnant women, adolescents (15-19 y) had higher sTfR concentrations than adults aged 20-34 y but not compared to adults aged 35-49 y; NHB women (compared to NHW and MA women) and multiparous women (compared to nulliparous women) had higher sTfR concentrations. The derived cutoff values (97.5th percentile in a defined healthy reference population) for defining elevated sTfR in the US were 6.00 mg/l for children 1-5 y and 5.33 mg/l for non-pregnant women 15-49 y.

CONCLUSIONS

A different sTfR cutoff value may be needed in children and non-pregnant women to define ID.

Regulation of mRNA expression encoding chaperone and co-chaperone proteins of the glucocorticoid receptor in peripheral blood: association with depressive symptoms during pregnancy

BACKGROUND

Major depressive disorder during pregnancy associates with potentially detrimental consequences for mother and child. The current study examined peripheral blood gene expression as a potential biomarker for prenatal depressive symptoms.

METHOD

Maternal RNA from whole blood, plasma and the Beck Depression Inventory were collected longitudinally from preconception through the third trimester of pregnancy in 106 women with a lifetime history of mood or anxiety disorders. The expression of 16 genes in whole blood involved in glucorticoid receptor (GR) signaling was assessed using real-time polymerase chain reaction. In parallel, plasma concentrations of progesterone, estradiol and cortisol were measured. Finally, we assessed ex vivo GR sensitivity in peripheral blood cells from a subset of 29 women.

RESULTS

mRNA expression of a number of GR-complex regulating genes was up-regulated over pregnancy. Women with depressive symptoms showed significantly smaller increases in mRNA expression of four of these genes - FKBP5, BAG1, NCOA1 and PPID. Ex vivo stimulation assays showed that GR sensitivity diminished with progression of pregnancy and increasing maternal depressive symptoms. Plasma concentrations of gonadal steroids and cortisol did not differ over pregnancy between women with and without clinically relevant depressive symptoms.

CONCLUSIONS

The presence of prenatal depressive symptoms appears to be associated with altered regulation of GR sensitivity. Peripheral expression of GR co-chaperone genes may serve as a biomarker for risk of developing depressive symptoms during pregnancy. The presence of such biomarkers, if confirmed, could be utilized in treatment planning for women with a psychiatric history.

Increased yet iron-restricted erythropoiesis in postpartum mothers

Iron deficiency in the postpartum period is common and associated with impaired quality of life. Interpretation of ordinary laboratory parameters is considered to be simple in postpartum women, as normalization of pregnancy induced physiological changes is assumed to take place in the early postpartum period. We have studied changes in erythrocyte and iron parameters during the first 11 postpartum months. Erythrocyte parameters and iron markers, serum ferritin, and soluble transferrin receptor (sTfR), and an inflammation marker, neopterin, were investigated in healthy mothers 6 weeks (n = 104), 4 months (n = 100), and 11 months (n = 43) after giving birth to a term infant. Healthy nonpregnant and nonlactating women (n = 61) were included as controls. The hemoglobin level increased throughout the first 11 postpartum months and was significantly higher from 4 months on, compared to control women. At all time points, the mothers had significantly lower mean corpuscular volume (MCV) and higher erythrocyte count and percentage of hypochromic erythrocytes. sTfR levels were significantly higher over the whole serum ferritin distribution during the first 4 postpartum months compared to the controls, indicative of an increased cell production. At 6 weeks, postpartum mothers had higher neopterin levels and this was associated with markers of a low iron status, not including sTfR. Substantial changes in erythrocyte and iron parameters were observed in the postpartum period, consistent with an increased, but iron restricted erythropoiesis. The increased erythropoietic activity was reflected in higher sTfR concentrations. Given the vital role for iron in both mothers and infants, further studies are warranted for establishing proper cut off levels for sTfR as an iron marker in postpartum women.

Placental expression of the heme transporter, feline leukemia virus subgroup C receptor, is related to maternal iron status in pregnant adolescents

Little is known about the expression of heme transporters in human placenta and possible associations between these transporters and maternal or neonatal iron status. To address this area of research, relative protein expression of 2 heme transporters, Feline Leukemia Virus, Subgroup C, Receptor 1 (FLVCR1) and Breast Cancer Resistance Protein (BCRP), was assessed using Western-blot analysis in human placental tissue in relation to maternal/neonatal iron status and placental iron concentration. Placental FLVCR1 (n = 71) and BCRP (n = 83) expression were assessed at term (36.6-41.7 wk gestation) in a cohort of pregnant adolescents (13-18 y of age) at high-risk of iron deficiency. Both FLVCR1 and BCRP were detected in all placental samples assayed. Placental FLVCR1 expression was positively related to placental BCRP expression (n = 69; R(2) = 0.104; P < 0.05). Adolescents that were anemic at delivery had lower placental FLVCR1 expression (n = 49; P < 0.05). Placental FLVCR1 expression was positively associated with placental iron concentration at delivery (n = 61; R(2) = 0.064; P < 0.05). In contrast, placental BCRP expression was not significantly associated with maternal iron status or placental iron content. Both FLVCR1 and BCRP are highly expressed in human placental tissue, but only FLVCR1 was significantly inversely associated with maternal iron status and placental iron concentration. Further analysis is needed to explore potential functional roles of FLVCR1 in human placental iron transport.

Postpartum anemia I: definition, prevalence, causes, and consequences

This review provides a status on the definition, prevalence, causes, and consequences of anemia in women who have given childbirth, i.e., postpartum anemia. The diagnosis of iron deficiency anemia relies on a full blood count including hemoglobin, serum ferritin, and serum soluble transferrin receptor, which appear to be reliable indicators of anemia and iron status 1 week postpartum while serum transferrin saturation is an unreliable indicator several weeks after delivery. It is recommended that postpartum anemia should be defined by hemoglobin <110 g/L at 1 week postpartum and <120 g/L at 8 weeks postpartum. The major causes of postpartum anemia are prepartum anemia combined with acute bleeding anemia due blood losses at delivery. Normal peripartum blood losses are approximately 300 ml, but hemorrhage >500 ml occur in 5-6% of the women. In healthy women after normal delivery, the prevalence of anemia (hemoglobin <110 g/L) 1 week postpartum is 14% in iron-supplemented women and 24% in non-supplemented women. In consecutive series of European women, the prevalence of anemia 48 h after delivery is approximately 50%. In developing countries, the prevalence of postpartum anemia is in the range of 50-80%. Postpartum anemia is associated with an impaired quality of life, reduced cognitive abilities, emotional instability, and depression and constitutes a significant health problem in women of reproductive age.

An association between plasma ferritin concentrations measured 48 h after delivery and postpartum depression

CONTEXT

Iron deficiency is the most common nutritional problem experienced by childbearing women, and postpartum depression (PPD) is the most common psychiatric disorder seen during the first year after delivery. The possible link between iron deficiency and PPD is not clear.

OBJECTIVE

To evaluate whether iron status 48 h after delivery was associated with PPD. Our hypothesis was that iron deficiency would be associated with PPD.

DESIGN

This was a prospective cohort study of depression-free women studied in the postpartum period.

SETTING

Women who give birth at obstetric units in several general hospitals in Spain.

PARTICIPANTS

A subsample of 729 women was included in the present study after exclusion of women with high C-reactive protein (CRP) and other diseases known to interfere with iron metabolism.

MAIN OUTCOME MEASURES

We evaluated depressive symptoms at 48 h, 8 weeks and 32 weeks postpartum and used a diagnostic interview to confirm the diagnosis of major depression. A blood sample obtained 48 h after delivery was used to measure the following iron storage parameters: ferritin, transferrin (Tf), free iron and transferrin saturation (TfS) and the inflammatory marker CCRP.

RESULTS

Overall, the women in the study had low iron concentrations (8.8 ± 6.9 μmol/L) and low TfS (12.6 ± 9.6%) but normal ferritin and Tf concentrations. A total of 65 women (9%) developed PPD during the 32 week postpartum period; these women also had a lower ferritin concentration (15.4 ± 12.7 μg/L vs. 21.6 ± 13.5 μg/L, P = 0.002). A strong association between ferritin and PPD was observed (odds ratio = 3.73, 95% CI: 1.84-7.56; P = 0.0001 for ferritin cutoff value of 7.26 μg/L). In our study, ferritin concentrations have a high specificity but low sensitivity in predicting PPD.

CONCLUSIONS

These findings support the role of iron in the etiology of PPD and the use of ferritin as a marker of iron deficiency in the postpartum period. We believe that this topic deserves further investigation.

Assessment of iron status in US pregnant women from the National Health and Nutrition Examination Survey (NHANES), 1999-2006

BACKGROUND

Total body iron calculated from serum ferritin and soluble transferrin receptor concentrations allows for the evaluation of the full range of iron status.

OBJECTIVE

We described the distribution of total body iron and the prevalence of iron deficiency (ID) on the basis of total body iron in US pregnant women.

DESIGN

We examined data from the National Health and Nutrition Examination Survey (NHANES) in 1999-2006 for 1171 pregnant women.

RESULTS

ID prevalence (±SE) in US pregnant women, which was defined as total body iron <0 mg/kg, was 18.0 ± 1.4%. Pregnant women in the first trimester had a higher mean total body iron than did pregnant women in the second or third trimesters. ID prevalence in pregnant women increased significantly with each trimester (6.9 ± 2.2%, 14.3 ± 2.1%, and 29.5 ± 2.7% in the first, second, and third trimesters, respectively). Pregnant women with parity ≥2 had the lowest mean total body iron and the highest prevalence of ID compared with values for pregnant women with parity of 0 or 1. The ID prevalence in non-Hispanic white pregnant women was significantly lower than in Mexican American or non-Hispanic black pregnant women. The mean total body iron and the prevalence of ID did not differ by educational level or by family income.

CONCLUSIONS

To our knowledge, these are the first data on total body iron distributions for a representative sample of US pregnant women. Low total body iron is more prevalent in pregnant women in the second or third trimesters, in Mexican American pregnant women, in non-Hispanic black pregnant women, and in women with parity ≥2.

Iron status in pregnant women in the Republic of Seychelles

OBJECTIVE

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

DESIGN

A prospective study.

SETTING

Republic of Seychelles.

SUBJECTS

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

RESULTS

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

CONCLUSIONS

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

Assessment and interpretation of micronutrient status during pregnancy

Accurate assessment of maternal micronutrient status is critical to the prevention of suboptimal micronutrient status and anaemia during pregnancy. Measurement of Fe, folate and vitamin B12 status is complicated by adaptive changes to maternal and placental physiology that markedly affect concentrations of circulating micronutrients and their functional biomarkers. Validation of new assessment methods by comparison with gold standards is often prevented by ethical considerations. Antenatal screening in the UK is predominantly concerned with the detection of anaemia, although estimation of maternal Fe stores by serum ferritin at the start of antenatal care may be a more effective preventive strategy. Functional assessment of maternal anaemia is highly problematic, so instead reference data are used for its definition. The effect of mild-to-moderate anaemia on pregnancy outcome is unclear because of the crude nature of its assessment and the influence of confounding factors. Fe-deficient erythropoiesis may be detected by assessment of erythrocyte Zn protoporphyrin and reticulocyte Hb, although such measures may be unavailable in many clinical laboratories. Serum soluble transferrin receptor is highly responsive to tissue Fe deficiency and is less affected by inflammation than most other indicators. Direct inter-assay comparison of serum and erythrocyte folate values is inadvisable since recovery rates differ greatly between methods. Serum total homocysteine is a useful functional biomarker of both folate and vitamin B12 status but during pregnancy is influenced by other factors that reduce its sensitivity. Isotope-dilution liquid chromatography-tandem MS and serum holo-transcobalamin provide new opportunities to gain detailed data of folate species and vitamin B12 fractions in large samples.

Prepartum anaemia: prevention and treatment

This review focuses on the occurrence, prevention and treatment of anaemia during pregnancy in Western societies. Iron deficiency anaemia (IDA) is the most prevalent deficiency disorder and the most frequent form of anaemia in pregnant women. Minor causes of anaemia are folate and vitamin B12 deficiency, haemoglobinopathy and haemolytic anaemia. Anaemia is defined as haemoglobin of <110 g/L in the first and third trimester and <105 g/L in the second trimester. The diagnosis relies on haemoglobin, a full blood count and plasma ferritin, which can be supported by plasma transferrin saturation and serum soluble transferrin receptor. Among fertile, non-pregnant women, approximately 40% have ferritin of <or=30 microg/L, i.e. small or absent iron reserves and therefore an unfavourable iron status with respect to upcoming pregnancy. The prevalence of prepartum anaemia in the third trimester ranges 14-52% in women taking placebo and 0-25% in women taking iron supplements, dependent on the doses of iron. In studies incorporating serum ferritin, the frequency of IDA in placebo-treated women ranges 12-17% and in iron-supplemented women 0-3%. Requirements for absorbed iron increase during pregnancy from 0.8 mg/day in the first trimester to 7.5 mg/day in the third trimester, on the average approximately 4.4 mg/day, and dietary measures are inadequate to reduce the frequency of prepartum IDA. However, IDA is efficiently prevented by oral iron supplements in doses of 30-40 mg ferrous iron taken between meals from early pregnancy to delivery. Treatment of IDA should aim at replenishing body iron deficits by oral and/or intravenous administration of iron. In women with slight to moderate IDA, i.e. haemoglobin of 90-105 g/L, treatment with oral ferrous iron of approximately 100 mg/day between meals is the therapeutic option in the first and second trimester; haemoglobin should be checked after 2 weeks and provided an increase of >or=10 g/L, oral iron therapy has proved effective and should continue. Treatment with intravenous iron is superior to oral iron with respect to the haematological response. Intravenous iron is considered safe in the second and third trimester, while there is little experience in the first trimester. Intravenous iron of 600-1,200 mg should be considered: (1) as second option if oral iron fails to increase haemoglobin within 2 weeks; (2) as first option at profound IDA, i.e. haemoglobin of <90 g/L in any trimester beyond 14 weeks gestation; and (3) as first option for IDA in third trimester. Profound IDA has serious consequences for both woman and foetus and requires prompt intervention with intravenous iron. This is especially important for the safety of women who for various reasons oppose blood transfusions.

Comparison of plasma ferritin concentration with the ratio of plasma transferrin receptor to ferritin in estimating body iron stores: results of 4 intervention trials

BACKGROUND

Efforts to develop global programs for the control of iron deficiency require simple, low-cost, and accurate indicators of iron status.

OBJECTIVE

We aimed to compare estimates of body iron (BI) stores, as calculated from either plasma ferritin concentration alone (BI-ferritin) or the ratio of plasma transferrin receptor (TfR) to ferritin (BI-TfR/ferritin).

DESIGN

Data were analyzed from 4 previously completed, randomized intervention trials that enrolled infants, schoolchildren, or pregnant women (total n = 1189, after excluding subjects with elevated C-reactive protein).

RESULTS

The correlation coefficients between BI-ferritin and BI-TfR/ferritin were >0.95 for all studies. The kappa index ranged from 0.5 to 1.0. All of the sensitivities of BI-ferritin for identifying persons with low iron stores (defined as BI-TfR/ferritin < 0 mg/kg body wt) were >0.90. All of the specificities were >0.90 except the study of pregnant women (specificity = 0.66). The effect sizes of iron intervention trials were significantly greater for change in iron reserves estimated by BI-TfR/ferritin than by BI-ferritin in 2 studies with larger effect sizes (1.11 compared with 1.00 and 1.56 compared with 1.44, respectively; P < 0.05) and 1 study with medium effect size (0.70 compared with 0.57; P < 0.05). However, there were no significant differences between estimates of these effect sizes for 1 study with a medium effect size and 1 study with a smaller effect size (0.78 compared with 0.83 and 0.37 compared with 0.35, respectively; P > 0.2).

CONCLUSION

Plasma ferritin concentration alone provides a good approximation of total BI reserves, as estimated by BI-TfR/ferritin, on the basis of high correlation, sensitivity, and specificity among nonpregnant persons with unelevated C-reactive protein.

Nutritional status in pregnant adolescents: a systematic review of biochemical markers

Adolescent pregnancy is a major public health challenge for many industrialized countries and is associated with significant medical, nutritional, social and economic risk for mothers and their infants. Despite this, relatively little is known about the nutritional status of this population. The aim of this paper was to conduct a systematic review of the current evidence relating to the biochemical markers of nutritional status of pregnant adolescents living in industrialized countries. Six papers were identified that fulfilled the inclusion criteria, the majority of which were conducted in the United States. The studies were of variable quality and most failed to control for potential confounders which may have strongly influenced the findings. Due to limited research, conclusions cannot be drawn about the zinc and calcium status of pregnant adolescents, and data on folate and vitamin B(12) status appeared conflicting. There was some consensus among studies, however, to suggest that indicators of anaemia and iron status were compromised in pregnant adolescents, particularly during the third trimester of pregnancy. Chronological age did not appear to influence nutritional status, although there was some evidence to suggest that increasing gynaecologic age may positively influence plasma ferritin levels. Current research is limited by sampling and measurement bias, and research is urgently required to address these limitations. Further consideration should also be made of the influence of the role of socio-economic support on pregnant adolescents' nutritional status. The achievement of improved nutrition in pregnancy among adolescents requires multidisciplinary collaborations of adolescent healthcare providers, academics, professional organizations, policymakers, industry and service users. Only once this is achieved can adolescent nutrition, and adolescent nutrition in pregnancy, be significantly and sustainably optimized.

Association between arsenic exposure from drinking water and anemia during pregnancy

OBJECTIVE

Arsenic is associated with numerous health effects. We investigated the association between arsenic exposure from drinking water and anemia during pregnancy.

METHODS

We conducted a prospective cohort pregnancy study in two Chilean cities with contrasting drinking water arsenic levels: 40 microg/L versus <1 microg/L. This analysis included 810 women who gave birth to live, singleton infants and had at least one hemoglobin determination during pregnancy.

RESULTS

Arsenic exposed women were more likely to be anemic during pregnancy after adjusting for other factors. Furthermore, as pregnancy progressed, the prevalence of anemia rose more sharply among those in the exposed versus unexposed city: 49% versus 17%.

CONCLUSION

This study suggests an association between moderate arsenic in drinking water and anemia during pregnancy. Further research is needed to identify the specific types of anemia underlying the association.

Body iron and individual iron prophylaxis in pregnancy--should the iron dose be adjusted according to serum ferritin?

This study aims to evaluate iron prophylaxis in pregnant women from the individual aspect, i.e. according to serum ferritin levels at the beginning of pregnancy, and to assess which dose of iron would be adequate to prevent iron deficiency (ID) and iron deficiency anaemia (IDA) during pregnancy and postpartum. A randomised, double-blind study comprising 301 healthy Danish pregnant women allocated into four groups taking ferrous iron (as fumarate) in doses of 20 mg (n=74), 40 mg (n=76), 60 mg (n=77) and 80 mg (n=75) from 18 weeks gestation (inclusion) to 8 weeks postpartum. Iron status markers [serum ferritin, serum soluble transferrin receptor (sTfR), haemoglobin] were recorded at 18, 32 and 39 weeks gestation and 8 weeks postpartum. Body iron was calculated using the serum sTfR/serum ferritin ratio. ID was defined by serum ferritin <12 microg/l in pregnancy and <15 microg/l postpartum; IDA as serum ferritin <12 microg/l and haemoglobin <5th percentile in iron-replete pregnant women. Women in the iron supplement groups were stratified according to serum ferritin levels at inclusion; 50.7% had ferritin <or=30 microg/l, 37.7% ferritin 30-70 microg/l and 11.6% ferritin >70 microg/l. At 32 weeks, women with ferritin <or=30 microg/l had an ID frequency of: 20-mg group 54.1%, 40 mg 29.7%, 60 mg 24.4%, 80 mg 20.6% (p<0.001); women with ferritin >30 microg/l had an ID frequency of: 20-mg group 20.0%, 40 mg 13.9%, 60 mg 5.7%, 80 mg 5.1% (p<0.001). Women with ferritin >70 microg/l had no ID. Postpartum, ID was found in 4.7% in 20-mg group, 2.9% in group 40 mg and 0% in group 60 and 80 mg. IDA: At 32 weeks, women with ferritin <or=30 microg/l had an IDA frequency of: 20-mg group 2.7%, 40 mg 2.7%, 60 and 80 mg 0%; none of the women with ferritin >30 microg/l displayed IDA. Body iron at 18 weeks was 10.4 mg/kg, similar in the four iron groups. Later in pregnancy body iron declined significantly, being lower the 20 mg group, and similar in the 40, 60 and 80-mg groups. Postpartum body iron rose to inclusion levels being 9.3 mg/kg in the 20-mg group and 10.5 mg/kg in the 40-, 60- and 80-mg groups. This study gives an estimate of iron dosage in individual iron prophylaxis adjusted to serum ferritin levels in early pregnancy. In the prevention of ID, we suggest 80-100 mg ferrous iron/day to women having ferritin <or=30 microg/l and 40 mg ferrous iron/day to women having ferritin 31-70 mug/l. In the prevention of IDA, we suggest 40 mg ferrous iron/day to women having ferritin <or=70 microg/l. Women with ferritin >70 microg/l have no need for iron supplement.

Iron and pregnancy—a delicate balance

The review focuses on iron balance during pregnancy and postpartum in the Western affluent societies. Iron status and body iron can be monitored using serum ferritin, haemoglobin, serum soluble transferrin receptors (sTfR) and the sTfR/ferritin ratio. Requirements for absorbed iron increase during pregnancy from 0.8 mg/day in the first trimester to 7.5 mg/day in the third trimester. Average requirement during the entire gestation is approximately 4.4 mg/day. Intestinal iron absorption increases during pregnancy, but women with ample body iron reserves have lower absorption than those with depleted reserves, so increased absorption is, in part, due to progressive iron depletion. Apparently, women do not change dietary habits when they become pregnant. Non-pregnant Scandinavian women have a median dietary iron intake of approximately 9 mg/day, i.e. more than 90% of the women have an intake below the recommended approximately 18 mg/day. Non-pregnant women have a low iron status, 42% have serum ferritin levels <or=30 microg/l, i.e. small or depleted iron reserves and 2-4% have iron deficiency anaemia; only 14-20% have ferritin levels >70 microg/l corresponding to body iron of >or=500 mg. The association between high haemoglobin during gestation and a low birth weight of the newborns is caused by inappropriate haemodilution. In placebo-controlled studies on healthy pregnant women, there is no relationship between the women's haemoglobin and birth weight of the newborns and no increased frequency of preeclampsia in women taking iron supplements.

Risk of infant anemia is associated with exclusive breast-feeding and maternal anemia in a Mexican cohort

The WHO recommends exclusive breast-feeding (EBF) for the first 6 mo of life to decrease the burden of infectious disease. However, some are concerned about the effect of EBF >6 mo on iron status of children in developing countries in which anemia is prevalent. This study examines the risk of anemia in relation to the duration of EBF and maternal anemia in a birth cohort studied between March 1998 and April 2003. All infant birth weights were >or=2.2 kg. All mothers received home-based peer counseling to promote EBF. Infant feeding data were collected weekly. Nurses measured hemoglobin (Hb) values every 3 mo. Hb was measured in 183 infants at 9 mo of age. Anemia at 9 mo was defined as a Hb value <100 g/L. EBF was defined by WHO criteria and ranged in duration from 0 to 31 wk. At 9 mo, Hb (mean +/- SEM) was 114 +/- 0.9 g/L; 23 children (12.5%) had Hb levels <100 g/L. EBF >6 mo, but not EBF 4-6 mo, was associated with increased risk of infant anemia compared with EBF <4 mo (odds ratio=18.4, 95% CI=1.9, 174.0). Maternal anemia was independently (P=0.03) associated with a 3-fold increased risk of infant anemia. These associations were not explained by confounding with other maternal or infant factors. By linear regression, a lower infant Hb at 9 mo was associated with increased EBF duration among mothers who had a history of anemia (beta=-0.07, P=0.003), but not among mothers with no history of anemia. Infants who are exclusively breast-fed for >6 mo in developing countries may be at increased risk of anemia, especially among mothers with a poor iron status; greater attention to this issue is warranted.