Impact of prophylactic iron supplementation in healthy pregnant women on maternal iron status and birth outcome

Daily oral iron supplementation during pregnancy

BACKGROUND

Iron and folic acid supplementation have been recommended in pregnancy for anaemia prevention, and may improve other maternal, pregnancy, and infant outcomes.

OBJECTIVES

To examine the effects of daily oral iron supplementation during pregnancy, either alone or in combination with folic acid or with other vitamins and minerals, as an intervention in antenatal care.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Trials Registry on 18 January 2024 (including CENTRAL, MEDLINE, Embase, CINAHL, ClinicalTrials.gov, WHO's International Clinical Trials Registry Platform, conference proceedings), and searched reference lists of retrieved studies.

SELECTION CRITERIA

Randomised or quasi-randomised trials that evaluated the effects of oral supplementation with daily iron, iron + folic acid, or iron + other vitamins and minerals during pregnancy were included.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed trial eligibility, ascertained trustworthiness based on pre-defined criteria, assessed risk of bias, extracted data, and conducted checks for accuracy. We used the GRADE approach to assess the certainty of the evidence for primary outcomes. We anticipated high heterogeneity amongst trials; we pooled trial results using a random-effects model (average treatment effect).

MAIN RESULTS

We included 57 trials involving 48,971 women. A total of 40 trials compared the effects of daily oral supplements with iron to placebo or no iron; eight trials evaluated the effects of iron + folic acid compared to placebo or no iron + folic acid. Iron supplementation compared to placebo or no iron Maternal outcomes: Iron supplementation during pregnancy may reduce maternal anaemia (4.0% versus 7.4%; risk ratio (RR) 0.30, 95% confidence interval (CI) 0.20 to 0.47; 14 trials, 13,543 women; low-certainty evidence) and iron deficiency at term (44.0% versus 66.0%; RR 0.51, 95% CI 0.38 to 0.68; 8 trials, 2873 women; low-certainty evidence), and probably reduces maternal iron-deficiency anaemia at term (5.0% versus 18.4%; RR 0.41, 95% CI 0.26 to 0.63; 7 trials, 2704 women; moderate-certainty evidence), compared to placebo or no iron supplementation. There is probably little to no difference in maternal death (2 versus 4 events, RR 0.57, 95% CI 0.12 to 2.69; 3 trials, 14,060 women; moderate-certainty evidence). The evidence is very uncertain for adverse effects (21.6% versus 18.0%; RR 1.29, 95% CI 0.83 to 2.02; 12 trials, 2423 women; very low-certainty evidence) and severe anaemia (Hb < 70 g/L) in the second/third trimester (< 1% versus 3.6%; RR 0.22, 95% CI 0.01 to 3.20; 8 trials, 1398 women; very low-certainty evidence). No trials reported clinical malaria or infection during pregnancy. Infant outcomes: Women taking iron supplements are probably less likely to have infants with low birthweight (5.2% versus 6.1%; RR 0.84, 95% CI 0.72 to 0.99; 12 trials, 18,290 infants; moderate-certainty evidence), compared to placebo or no iron supplementation. However, the evidence is very uncertain for infant birthweight (MD 24.9 g, 95% CI -125.81 to 175.60; 16 trials, 18,554 infants; very low-certainty evidence). There is probably little to no difference in preterm birth (7.6% versus 8.2%; RR 0.93, 95% CI 0.84 to 1.02; 11 trials, 18,827 infants; moderate-certainty evidence) and there may be little to no difference in neonatal death (1.4% versus 1.5%, RR 0.98, 95% CI 0.77 to 1.24; 4 trials, 17,243 infants; low-certainty evidence) or congenital anomalies, including neural tube defects (41 versus 48 events; RR 0.88, 95% CI 0.58 to 1.33; 4 trials, 14,377 infants; low-certainty evidence). Iron + folic supplementation compared to placebo or no iron + folic acid Maternal outcomes: Daily oral supplementation with iron + folic acid probably reduces maternal anaemia at term (12.1% versus 25.5%; RR 0.44, 95% CI 0.30 to 0.64; 4 trials, 1962 women; moderate-certainty evidence), and may reduce maternal iron deficiency at term (3.6% versus 15%; RR 0.24, 95% CI 0.06 to 0.99; 1 trial, 131 women; low-certainty evidence), compared to placebo or no iron + folic acid. The evidence is very uncertain about the effects of iron + folic acid on maternal iron-deficiency anaemia (10.8% versus 25%; RR 0.43, 95% CI 0.17 to 1.09; 1 trial, 131 women; very low-certainty evidence), or maternal deaths (no events; 1 trial; very low-certainty evidence). The evidence is uncertain for adverse effects (21.0% versus 0.0%; RR 44.32, 95% CI 2.77 to 709.09; 1 trial, 456 women; low-certainty evidence), and the evidence is very uncertain for severe anaemia in the second or third trimester (< 1% versus 5.6%; RR 0.12, 95% CI 0.02 to 0.63; 4 trials, 506 women; very low-certainty evidence), compared to placebo or no iron + folic acid. Infant outcomes: There may be little to no difference in infant low birthweight (33.4% versus 40.2%; RR 1.07, 95% CI 0.31 to 3.74; 2 trials, 1311 infants; low-certainty evidence), comparing iron + folic acid supplementation to placebo or no iron + folic acid. Infants born to women who received iron + folic acid during pregnancy probably had higher birthweight (MD 57.73 g, 95% CI 7.66 to 107.79; 2 trials, 1365 infants; moderate-certainty evidence), compared to placebo or no iron + folic acid. There may be little to no difference in other infant outcomes, including preterm birth (19.4% versus 19.2%; RR 1.55, 95% CI 0.40 to 6.00; 3 trials, 1497 infants; low-certainty evidence), neonatal death (3.4% versus 4.2%; RR 0.81, 95% CI 0.51 to 1.30; 1 trial, 1793 infants; low-certainty evidence), or congenital anomalies (1.7% versus 2.4; RR 0.70, 95% CI 0.35 to 1.40; 1 trial, 1652 infants; low-certainty evidence), comparing iron + folic acid supplementation to placebo or no iron + folic acid. A total of 19 trials were conducted in malaria-endemic countries, or in settings with some malaria risk. No studies reported maternal clinical malaria; one study reported data on placental malaria.

AUTHORS' CONCLUSIONS

Daily oral iron supplementation during pregnancy may reduce maternal anaemia and iron deficiency at term. For other maternal and infant outcomes, there was little to no difference between groups or the evidence was uncertain. Future research is needed to examine the effects of iron supplementation on other maternal and infant health outcomes, including infant iron status, growth, and development.

Scientific opinion on the tolerable upper intake level for iron

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the tolerable upper intake level (UL) for iron. Systematic reviews were conducted to identify evidence regarding high iron intakes and risk of chronic diseases, adverse gastrointestinal effects and adverse effects of iron supplementation in infancy, young childhood and pregnancy. It is established that systemic iron overload leads to organ toxicity, but no UL could be established. The only indicator for which a dose-response could be established was black stools, which reflect the presence of large amounts of unabsorbed iron in the gut. This is a conservative endpoint among the chain of events that may lead to systemic iron overload but is not adverse per se. Based on interventions in which black stools did not occur at supplemental iron intakes of 20-25 mg/day (added to a background intake of 15 mg/day), a safe level of intake for iron of 40 mg/day for adults (including pregnant and lactating women) was established. Using allometric scaling (body weight0.75), this value was scaled down to children and adolescents and safe levels of intakes between 10 mg/day (1-3 years) and 35 mg/day (15-17 years) were derived. For infants 7-11 months of age who have a higher iron requirement than young children, allometric scaling was applied to the supplemental iron intakes (i.e. 25 mg/day) and resulted in a safe level of supplemental iron intake of 5 mg/day. This value was extended to 4-6 month-old infants and refers to iron intakes from fortified foods and food supplements, not from infant and follow-on formulae. The application of the safe level of intake is more limited than a UL because the intake level at which the risk of adverse effects starts to increase is not defined.

Effect of Prenatal Iron Supplementation Adapted to Hemoglobin Levels in Early Pregnancy on Fetal and Neonatal Growth-ECLIPSES Study

In this randomized clinical trial, we evaluated the effects of prenatal iron supplementation adapted to pregnant women's initial hemoglobin (Hb) levels on fetal growth parameters until birth in women from the Mediterranean coast of northern Spain. All (n = 791) women were iron-supplemented during pregnancy according to Hb levels at the 12th gestational week: stratum 1 (Hb: 110-130 g/L) received 40 or 80 mg iron daily; stratum 2 (Hb > 130 g/L) received 40 or 20 mg iron daily. Fetal biometric and anthropometric measurements were evaluated in the three trimesters and at birth, respectively. In stratum 1, using 80 mg/d instead of 40 mg/d increased the risk of fetal head circumference > 90th percentile (OR = 2.49, p = 0.015) at the second trimester and fetal weight (OR = 2.36, p = 0.011) and femur length (OR = 2.50, p = 0.018) < 10th percentile at the third trimester. For stratum 2, using 40 mg/d instead of 20 mg/d increased the risk of fetal head circumference > 90th percentile (OR = 3.19, p = 0.039) at the third trimester. A higher risk of delivering an LGA baby (OR = 2.35, p = 0.015) for birthweight was also observed in stratum 1 women receiving 80 mg/d. It is crucial to adjust the prenatal iron supplementation to each pregnant woman's needs, i.e., adapted to their initial Hb levels, to achieve optimal fetal development, since excessive iron doses appear to adversely influence fetal growth.

Iron supplements in pregnant women with normal iron status: A systematic review and meta-analysis

INTRODUCTION

Effects of daily iron supplementation in iron replete pregnancy are unclear. This systematic review aimed to assess benefits and harms of oral iron supplements in pregnant women without anemia and iron deficiency.

MATERIAL AND METHODS

We predefined and registered a protocol in PROSPERO (CRD42020186210) and performed the review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. We searched for randomized clinical trials (RCTs) and observational studies comparing daily oral iron supplementation with no iron supplements in non-anemic iron replete pregnant women. Searches were conducted in MEDLINE (by PubMed), EMBASE (by OVID), Cochrane Library, and ClinicalTrials.gov from inception to September 2022 without language restrictions. Two authors independently screened records, extracted data, and assessed risk of bias using the revised Cochrane risk of bias tool (RoB2). One author read full-texts, assessed certainty of evidence by GRADE and conducted meta-analyses using a random-effects model. Primary outcomes included iron deficiency anemia, iron deficiency, hemoglobin >130 g/L, elevated iron status, small for gestational age newborns, low birthweight newborns, preterm birth, and congenital anomalies.

RESULTS

Eight RCTs (2822 women) but no observational studies were eligible for inclusion. Daily oral iron supplementation in pregnancy probably reduces iron deficiency anemia at term (risk ratio [RR]: 0.51, 95% confidence interval [CI]: 0.38-0.70; 4 RCTs, 1670 women; I2  = 13%; moderate-certainty evidence) and the incidence of low birthweight babies (RR: 0.30, 95% CI: 0.13-0.68; 2 RCTs, 361 infants; I2  = 0%; moderate-certainty evidence). In addition, it may reduce iron deficiency at term (RR: 0.74, 95% CI: 0.60-0.92; 4 RCTs, 1663 women; I2  = 58%; low-certainty evidence) and the incidence of small for gestational age babies (RR: 0.39, 95% CI: 0.17-0.86; 1 RCT, 213 infants; I2 not estimable; low-certainty evidence).

CONCLUSIONS

Daily iron supplementation in iron replete non-anemic pregnant women probably reduces the risk of maternal iron deficiency anemia at term and low birthweight.

Effect of Nutrition Interventions Before and/or During Early Pregnancy on Low Birth Weight in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

BACKGROUND

This review aimed at synthesizing evidence on the effectiveness of nutritional interventions that were carried out before and/or during early pregnancy versus the control groups on reducing the risk of low weight at birth in sub-Saharan Africa.

METHODS

We have searched on MEDLINE, SCOPUS, CINAHL, HINARI, and Cochrane Library of systematic review databases for published articles in English language from 2010 to 2021 years. For unpublished studies, we searched on Google scholar. Randomized controlled trial studies of nutritional interventions carried out before/or during early pregnancy in sub-Saharan Africa to improve low birth weight were considered. The data were extracted and pooled using the Joanna Briggs Institute software. The effect size was calculated using fixed-effect models. Mantel-Haenszel method was used to calculate the relative risk with their respective 95% CI. Heterogeneity was assessed using the standard chi-square and I ² tests.

RESULTS

Seven studies were included in the review with a total of 5934 participants. Three types of nutritional interventions were identified: iron supplementations, lipid-based supplementations, and nutritional education and counseling. We have identified only one intervention started during preconception. The meta-analysis showed that none of the identified nutrition interventions had a statistically significant effect on low birth weight.

CONCLUSIONS

Based on the review evidence, nutritional interventions before and/or during early pregnancy in sub-Saharan Africa had no significant effect on low birth weight. However, since our evidence was derived from a small number of trials and participants, a large-scale randomized controlled trials review might be required to elucidate the finding.

Diagnosis and Therapy of Iron Deficiency Anemia During Pregnancy: Recommendation of the Austrian Society for Gynecology and Obstetrics (OEGGG)

This overview analyzes the data on the controversial therapy of iron substitution during pregnancy, the diagnosis of iron deficiency anemia and the indication-related therapy, and is the first recommendation issued by the OEGGG on the appropriate therapy. The effects of anemia during pregnancy on postnatal outcomes have been intensively investigated with heterogeneous results. A final scientific conclusion with regards to the "optimal" maternal hemoglobin level is limited by the heterogeneous results of various studies, many of which were conducted in emerging nations (with different dietary habits and structural differences in the respective healthcare systems). The current literature even suggests that there may be a connection between both decreased and increased maternal serum hemoglobin concentrations and unfavorable short-term and long-term neonatal outcomes. In Austria, 67 percent of pregnant women take pharmacological supplements or use a variety of dietary supplements. Clinically, the prevalence of maternal anemia is often overestimated, leading to overtreatment of pregnant women (iron substitution without a medical indication). To obtain a differential diagnosis, a workup of the indications for treatment should be carried out prior to initiating any form of iron substitution during pregnancy. If treatment is medically indicated, oral iron substitution is usually sufficient. Because of the restricted approval and potential side effects, medical indications for intravenous iron substitution should be limited. Intravenous iron substitution without a prior detailed diagnostic workup is an off-label use and should only be used in very limited cases, and women should be advised accordingly.

Effects of vitamin and mineral supplementation during pregnancy on maternal, birth, child health and development outcomes in low- and middle-income countries: A systematic review

Background

Almost two billion people who are deficient in vitamins and minerals are women and children in low- and middle-income countries (LMIC). These deficiencies are worsened during pregnancy due to increased energy and nutritional demands, causing adverse outcomes in mother and child. To reduce micronutrient deficiencies, several strategies have been implemented, including diet diversification, large-scale and targeted fortification, staple crop bio-fortification and micronutrient supplementation.

Objectives

To evaluate and summarize the available evidence on the effects of micronutrient supplementation during pregnancy in LMIC on maternal, fetal, child health and child development outcomes. This review will assess the impact of single micronutrient supplementation (calcium, vitamin A, iron, vitamin D, iodine, zinc, vitamin B12), iron-folic acid (IFA) supplementation, multiple micronutrient (MMN) supplementation, and lipid-based nutrient supplementation (LNS) during pregnancy.

Search Methods

We searched papers published from 1995 to 31 October 2019 (related programmes and good quality studies pre-1995 were limited) in CAB Abstracts, CINAHL, Cochrane Central Register of Controlled Trials, Embase, International Initiative for Impact Evaluations, LILACS, Medline, POPLINE, Web of Science, WHOLIS, ProQuest Dissertations & Theses Global, R4D, WHO International Clinical Trials Registry Platform. Non-indexed grey literature searches were conducted using Google, Google Scholar, and web pages of key international nutrition agencies.

Selection Criteria

We included randomized controlled trials (individual and cluster-randomized) and quasi-experimental studies that evaluated micronutrient supplementation in healthy, pregnant women of any age and parity living in a LMIC. LMIC were defined by the World Bank Group at the time of the search for this review. While the aim was to include healthy pregnant women, it is likely that these populations had one or more micronutrient deficiencies at baseline; women were not excluded on this basis.

Data Collection and Analysis

Two authors independently assessed studies for inclusion and risk of bias, and conducted data extraction. Data were matched to check for accuracy. Quality of evidence was assessed using the GRADE approach.

Main Results

A total of 314 papers across 72 studies (451,723 women) were eligible for inclusion, of which 64 studies (439,649 women) contributed to meta-analyses. Seven studies assessed iron-folic acid (IFA) supplementation versus folic acid; 34 studies assessed MMN vs. IFA; 4 studies assessed LNS vs. MMN; 13 evaluated iron; 13 assessed zinc; 9 evaluated vitamin A; 11 assessed vitamin D; and 6 assessed calcium. Several studies were eligible for inclusion in multiple types of supplementation. IFA compared to folic acid showed a large and significant (48%) reduction in the risk of maternal anaemia (average risk ratio (RR) 0.52, 95% CI 0.41 to 0.66; studies = 5; participants = 15,540; moderate-quality evidence). As well, IFA supplementation demonstrated a smaller but significant, 12% reduction in risk of low birthweight (LBW) babies (average RR 0.88, 95% CI 0.78 to 0.99; studies = 4; participants = 17,257; high-quality evidence). MMN supplementation was defined as any supplement that contained at least 3 micronutrients. Post-hoc analyses were conducted, where possible, comparing the differences in effect of MMN with 4+ components and MMN with 3 or 4 components. When compared to iron with or without FA, MMN supplementation reduced the risk of LBW by 15% (average RR 0.85, 95% CI 0.77 to 0.93; studies = 28; participants = 79,972); this effect was greater in MMN with >4 micronutrients (average RR 0.79, 95% CI 0.71 to 0.88; studies = 19; participants = 68,138 versus average RR 1.01, 95% CI 0.92 to 1.11; studies = 9; participants = 11,834). There was a small and significant reduction in the risk of stillbirths (average RR 0.91; 95% CI 0.86 to 0.98; studies = 22; participants = 96,772) and a small and significant effect on the risk of small-for-gestational age (SGA) (average RR 0.93; 95% CI 0.88 to 0.98; studies = 19; participants = 52,965). For stillbirths and SGA, the effects were greater among those provided MMN with 4+ micronutrients. Children whose mothers had been supplemented with MMN, compared to IFA, demonstrated a 16% reduced risk of diarrhea (average RR 0.84; 95% CI 0.76 to 0.92; studies = 4; participants = 3,142). LNS supplementation, compared to MMN, made no difference to any outcome; however, the evidence is limited. Iron supplementation, when compared to no iron or placebo, showed a large and significant effect on maternal anaemia, a reduction of 47% (average RR 0.53, 95% CI 0.43 to 0.65; studies = 6; participants = 15,737; moderate-quality evidence) and a small and significant effect on LBW (average RR 0.88, 95% CI 0.78 to 0.99; studies = 4; participants = 17,257; high-quality evidence). Zinc and vitamin A supplementation, each both compared to placebo, had no impact on any outcome examined with the exception of potentially improving serum/plasma zinc (mean difference (MD) 0.43 umol/L; 95% CI -0.04 to 0.89; studies = 5; participants = 1,202) and serum/plasma retinol (MD 0.13 umol/L; 95% CI -0.03 to 0.30; studies = 6; participants = 1,654), respectively. When compared to placebo, vitamin D supplementation may have reduced the risk of preterm births (average RR 0.64; 95% CI 0.40 to 1.04; studies = 7; participants = 1,262), though the upper CI just crosses the line of no effect. Similarly, calcium supplementation versus placebo may have improved rates of pre-eclampsia/eclampsia (average RR 0.45; 95% CI 0.19 to 1.06; studies = 4; participants = 9,616), though the upper CI just crosses 1.

Authors' Conclusions

The findings suggest that MMN and vitamin supplementation improve maternal and child health outcomes, including maternal anaemia, LBW, preterm birth, SGA, stillbirths, micronutrient deficiencies, and morbidities, including pre-eclampsia/eclampsia and diarrhea among children. MMN supplementation demonstrated a beneficial impact on the most number of outcomes. In addition, MMN with >4 micronutrients appeared to be more impactful than MMN with only 3 or 4 micronutrients included in the tablet. Very few studies conducted longitudinal analysis on longer-term health outcomes for the child, such as anthropometric measures and developmental outcomes; this may be an important area for future research. This review may provide some basis to guide continual discourse around replacing IFA supplementation with MMN along with the use of single micronutrient supplementation programs for specific outcomes.

Association between Iron Supplementation, Dietary Iron Intake and Risk of Moderate Preterm Birth: A Birth Cohort Study in China

Background:

To evaluate the independent and collective effects of maternal iron supplementation and dietary iron intake upon the risk of moderate preterm birth and its subtypes.

Methods:

In this birth cohort study, 1019 pregnant women with moderate preterm birth and 9160 women with term birth were recruited at Gansu Provincial Maternity and Child Care Hospital from 2010–2012 in China. Unconditional logistic regression models were utilized to evaluate the association between maternal iron supplementation, dietary iron intake, and the risk of moderate preterm birth and its subtypes.

Results:

Compared with non-users, iron supplement users exerted a protective effect upon the overall (OR=0.54, 95%CI=0.40–0.72) and spontaneous moderate preterm birth (OR=0.39, 95%CI=0.33–0.83). Compared with the 25^th quartiles of dietary iron intake, either before or during pregnancy, it exerted a significantly protective effect upon those who had the highest quartiles of dietary iron intake (OR=0.87, 95%CI=0.82–0.95 for the highest quartiles of dietary iron intake before pregnancy OR=0.85, 95%CI=0.79–0.91). Positive association was observed between the additive scale and multiplicative scale for preterm birth, spontaneous preterm rather than medically indicated preterm.

Conclusion:

Iron supplements (60 mg/day) and high-iron intake (>25.86 mg/day before pregnancy, >30.46 mg/day during pregnancy) reduced the risk of moderate preterm birth. Positive correlation is found between the additive scale and multiplicative scale for preterm birth, spontaneous preterm birth.

Effects of Maternal Nutritional Supplements and Dietary Interventions on Placental Complications: An Umbrella Review, Meta-Analysis and Evidence Map

The placenta is a vital, multi-functional organ that acts as an interface between maternal and fetal circulation during pregnancy. Nutritional deficiencies during pregnancy alter placental development and function, leading to adverse pregnancy outcomes, such as pre-eclampsia, infants with small for gestational age and low birthweight, preterm birth, stillbirths and maternal mortality. Maternal nutritional supplementation may help to mitigate the risks, but the evidence base is difficult to navigate. The primary purpose of this umbrella review is to map the evidence on the effects of maternal nutritional supplements and dietary interventions on pregnancy outcomes related to placental disorders and maternal mortality. A systematic search was performed on seven electronic databases, the PROSPERO register and references lists of identified papers. The results were screened in a three-stage process based on title, abstract and full-text by two independent reviewers. Randomized controlled trial meta-analyses on the efficacy of maternal nutritional supplements or dietary interventions were included. There were 91 meta-analyses included, covering 23 types of supplements and three types of dietary interventions. We found evidence that supports supplementary vitamin D and/or calcium, omega-3, multiple micronutrients, lipid-based nutrients, and balanced protein energy in reducing the risks of adverse maternal and fetal health outcomes. However, these findings are limited by poor quality of evidence. Nutrient combinations show promise and support a paradigm shift to maternal dietary balance, rather than single micronutrient deficiencies, to improve maternal and fetal health. The review is registered at PROSPERO (CRD42020160887).

Differences in the response to iron supplementation on oxidative stress, inflammation, and hematological parameters in nonanemic and anemic pregnant women

Background: Iron supplementation is widely recommended for all pregnant women, irrespective of their iron status. But providing excess iron to nonanemic pregnant women can result in iron overload, which may lead to oxidative stress and inflammation.Objectives: To assess the differential effect of iron supplementation on hematological parameters, oxidative stress, and inflammation in nonanemic and anemic pregnant women.Methods: Forty nonanemic and forty anemic pregnant women were recruited at 12 weeks of gestation. The study subjects were supplemented with iron (60 mg/day for nonanemic pregnant women and 120 mg/day for anemic pregnant women). Fasting state blood samples were collected at 12 and 28 weeks of gestation.Results: Malondialdehyde (MDA)/total antioxidant status (TAS) ratio (MDA/TAS) and high-sensitivity C-reactive protein (hsCRP) were significantly higher in anemic pregnant women before iron supplementation. Iron supplementation to the anemic pregnant women resulted in significant improvement in the hematological profile and ferritin levels. Further, the iron supplementation caused a significant reduction in hsCRP levels although the MDA/TAS ratio remained unaltered. Iron supplementation to nonanemic pregnant women resulted in a significant increase in the levels of MDA/TAS ratio and hsCRP, but there were no changes in hematological profile and serum ferritin levels.Conclusion: Prophylactic iron supplementation in nonanemic pregnant women increased oxidative stress and inflammation. However, in anemic pregnant women, iron supplementation was found to be beneficial as it improved hematological status and decreased inflammation without affecting oxidative stress.

Vitamin and Mineral Supplementation During Pregnancy on Maternal, Birth, Child Health and Development Outcomes in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis

Almost two billion people are deficient in key vitamins and minerals, mostly women and children in low- and middle-income countries (LMICs). Deficiencies worsen during pregnancy due to increased energy and nutritional demands, causing adverse outcomes in mother and child, but could be mitigated by interventions like micronutrient supplementation. To our knowledge, this is the first systematic review that aimed to compile evidence from both efficacy and effectiveness trials, evaluating different supplementation interventions on maternal, birth, child health, and developmental outcomes. We evaluated randomized controlled trials and quasi-experimental studies published since 1995 in peer-reviewed and grey literature that assessed the effects of calcium, vitamin A, iron, vitamin D, and zinc supplementation compared to placebo/no treatment; iron-folic (IFA) supplementation compared to folic acid only; multiple micronutrient (MMN) supplementation compared to IFA; and lipid-based nutrient supplementation (LNS) compared to MMN supplementation. Seventy-two studies, which collectively involved 314 papers (451,723 women), were included. Meta-analyses showed improvement in several key birth outcomes, such as preterm birth, small-for-gestational age (SGA) and low birthweight with MMN supplementation, compared to IFA. MMN also improved child outcomes, including diarrhea incidence and retinol concentration, which are findings not previously reported. Across all comparisons, micronutrient supplementation had little to no effect on mortality (maternal, neonatal, perinatal, and infant) outcomes, which is consistent with other systematic reviews. IFA supplementation showed notable improvement in maternal anemia and the reduction in low birthweight, whereas LNS supplementation had no apparent effect on outcomes; further research that compares LNS and MMN supplementation could help understand differences with these commodities. For single micronutrient supplementation, improvements were noted in only a few outcomes, mainly pre-eclampsia/eclampsia (calcium), maternal anemia (iron), preterm births (vitamin D), and maternal serum zinc concentration (zinc). These findings highlight that micronutrient-specific supplementation should be tailored to specific groups or needs for maximum benefit. In addition, they further contribute to the ongoing discourse of choosing antenatal MMN over IFA as the standard of care in LMICs.

Oral iron-based interventions for prevention of critical outcomes in pregnancy and postnatal care: An overview and update of systematic reviews

OBJECTIVE

The aim of this work was to summarize and update the evidence concerning oral iron-based interventions compared to placebo or no iron-based interventions to prevent critical outcomes in pregnancy or treat critical outcomes in the postpartum phase.

METHOD

Published systematic reviews (Feb 2018) and primary studies (from 2015 to March 2018) retrieved from MEDLINE, EMBASE, and the Cochrane Library were examined. The AMSTAR (Assessing the Methodological Quality of Systematic Reviews) tool was used to assess the quality of reviews. GRADE was used to rate the quality of the evidence for critical outcomes.

RESULTS

Antenatal care: Compared to placebo/no treatment, iron-based therapies reduced maternal anemia at term by 59% (seven trials at low risk of bias, RR 0.41, 95% CI 0.23-0.73; I²  = 86%; moderate-quality evidence) and maternal iron deficiency anemia by 67% (RR 0.33, 95% CI 0.16-0.69; I²  = 49%). There was no evidence of difference between iron-based therapies vs control in terms of side effects (RR 1.42, 95% CI 0.91-2.21), preterm delivery (13 studies: RR 0.93, 95% CI 0.84-1.03; low-quality evidence), low birthweight (RR 0.94, 95% CI 0.79-1.13; low-quality evidence) and infant mortality (RR 0.93, 0.72-1.20; low-quality evidence).

POSTNATAL CARE

There was insufficient evidence to determine whether iron-based therapies can reduce postpartum anemia.

CONCLUSION

Iron supplementation is effective in preventing maternal anemia at term but not low birthweight, preterm delivery or infant mortality.

Prophylactic Iron Supplementation in Pregnancy: A Controversial Issue

In our world today, iron deficiency (ID) is the most frequent nutritional deficiency and it is being considered as an epidemic public health crisis. Women of reproductive age and infants are at particular risk of ID, especially in underdeveloped countries. During pregnancy, iron deficiency anemia is a specific risk factor associated with negative maternal and perinatal outcomes. Many countries have iron supplementation (IS) programs-as recommended by the World Health Organization-during pregnancy; however, IS clinical benefits and risks are unclear. This review aims to discuss the threats and benefits of routine IS on maternal and infant outcomes.

Modifying effects of maternal Hb concentration on infant birth weight in women receiving prenatal iron-containing supplements: a randomised controlled trial

Concerns have been raised about the benefits of Fe-containing supplements on infant birth weight among women with normal/high Hb levels at baseline. Thus far, no clinical trials have examined whether the effects of prenatal Fe-containing supplements on birth weight vary by maternal Hb levels. We compared the effects of Fe-folic acid (IFA) or multiple micronutrients (MMN) with folic acid (FA) supplements on birth weight among pregnant women with mild/no anaemia or high Hb levels. A double-blind randomised controlled trial was conducted in 2006-2009. In total, 18 775 pregnant women with mild/no anaemia (145 g/l) baseline Hb levels, IFA and MMN supplements increased birth weight by 91·44 (95% CI 3·37, 179·51) g and 107·63 (95% CI 21·98, 193·28) g (P<0·05), respectively, compared with the FA group. No differences were found between the IFA and the MMN group, regardless of maternal Hb concentration. In conclusion, the effects of Fe-containing supplements on birth weight depended on baseline Hb concentrations. The Fe-containing supplements improved birth weight in women with very high Hb levels before 20 weeks of gestation.

Systematic review of randomized trials of the effect of iron supplementation on iron stores and oxygen carrying capacity in pregnancy

INTRODUCTION

Anemia in pregnancy affects 25% of all pregnancies in Europe with iron deficiency affecting even more. Despite supplementation, iron deficiency persists. This review will assess the effect on serum ferritin (iron stores) and hemoglobin (oxygen-carrying capacity) following iron supplementation in pregnant women with anemic and non-anemic iron deficiency.

MATERIAL AND METHODS

A systemic search of electronic databases and trial registers was conducted from inception to January 2014. Randomized controlled trials of iron supplementation that measured serum ferritin and hemoglobin levels before and after supplementation were selected. Two independent reviewers selected studies, extracted data and assessed quality. Descriptive analyses were carried out.

RESULTS

The review included 23 randomized controlled trials (3525 women). In iron deficiency anemia, more studies described statistically significant increases in serum ferritin levels than in hemoglobin levels following intravenous iron supplementation. In non-anemic iron deficiency there were more statistically significant increases in serum ferritin levels than in hemoglobin levels following oral supplementation. There were no studies reporting maternal quality of life outcomes.

CONCLUSIONS

Serum ferritin appears to change more than hemoglobin following iron supplementation. The clinical effects of this need further investigation.

Screening for Iron Deficiency Anemia and Iron Supplementation in Pregnant Women to Improve Maternal Health and Birth Outcomes: U.S. Preventive Services Task Force Recommendation Statement

DESCRIPTION

Update of the 2006 U.S. Preventive Services Task Force (USPSTF) recommendation on screening for iron deficiency anemia.

METHODS

The USPSTF reviewed the evidence on the association between change in iron status as a result of intervention (oral supplementation or treatment) in pregnant women and adolescents and improvement in maternal and infant health outcomes.

POPULATION

This recommendation applies to pregnant women and adolescents living in the United States who do not have symptoms of iron deficiency anemia. It does not address pregnant women who are malnourished, have symptoms of iron deficiency anemia, or have special hematologic conditions or nutritional needs that may increase their need for iron.

RECOMMENDATIONS

The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for iron deficiency anemia in pregnant women to prevent adverse maternal health and birth outcomes. (I statement). The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of routine iron supplementation for pregnant women to prevent adverse maternal health and birth outcomes. (I statement).

Iron Supplementation in Iron-Replete and Nonanemic Pregnant Women in Tanzania: A Randomized Clinical Trial

IMPORTANCE

Anemia is common in pregnancy and increases the risk of adverse outcomes. Iron deficiency is a leading cause of anemia in sub-Saharan Africa, and iron supplementation is the standard of care during pregnancy; however, recent trials among children have raised concerns regarding the safety of iron supplementation in malaria-endemic regions. There is limited evidence on the safety of iron supplementation during pregnancy in these areas.

OBJECTIVE

To evaluate the safety and efficacy of iron supplementation during pregnancy in a malaria-endemic region.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a randomized, double-blind, placebo-controlled clinical trial among pregnant women presenting for antenatal care in Dar es Salaam, Tanzania, from September 28, 2010, through October 4, 2012. Iron-replete, nonanemic women were eligible if they were uninfected with human immunodeficiency virus, primigravidae or secundigravidae, and at or before 27 weeks of gestation. Screening of 21,316 women continued until the target enrollment of 1500 was reached. Analyses followed the intent-to-treat principle and included all randomized participants.

INTERVENTIONS

Participants were randomized to receive 60 mg of iron or placebo, returning every 4 weeks for standard prenatal care, including malaria screening, prophylaxis with the combination of sulfadoxine and pyrimethamine, and treatment, as needed.

MAIN OUTCOMES AND MEASURES

The primary outcomes were placental malaria, maternal hemoglobin level at delivery, and birth weight.

RESULTS

Among 1500 study participants (750 randomized for each group), 731 in iron group and 738 in placebo group had known birth outcomes and 493 in iron group and 510 in placebo group had placental samples included in the analysis. Maternal characteristics were similar at baseline in the iron and placebo groups, and 1354 (91.7%) used malaria control measures. The risk of placental malaria was not increased by maternal iron supplementation (relative risk [RR], 1.03; 95% CI, 0.65-1.65), and iron supplementation did not significantly affect birth weight (3155 vs 3137 g, P = .89). Compared with placebo, iron supplementation significantly improved the mean increase from baseline to delivery for hemoglobin (0.1 vs -0.7 g/dL, P < .001) and serum ferritin (41.3 vs 11.3 µg/L, P < .001). Iron supplementation significantly decreased the risk of anemia at delivery by 40% (RR, 0.60; 95% CI, 0.51-0.71) but not severe anemia (RR, 0.68; 95% CI, 0.41-1.14). Iron supplementation significantly reduced the risk of maternal iron deficiency at delivery by 52% (RR, 0.48; 95% CI, 0.32-0.70) and the risk of iron deficiency anemia by 66% (RR, 0.34; 95% CI, 0.19-0.62).

CONCLUSIONS AND RELEVANCE

Prenatal iron supplementation among iron-replete, nonanemic women was not associated with an increased risk of placental malaria or other adverse events in the context of good malaria control. Participants receiving supplementation had improved hematologic and iron status at delivery compared with the placebo group. These findings provide support for continued administration of iron during pregnancy in malaria-endemic regions.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01119612.

Daily oral iron supplementation during pregnancy

BACKGROUND

Iron and folic acid supplementation has been the preferred intervention to improve iron stores and prevent anaemia among pregnant women, and it is thought to improve other maternal and birth outcomes.

OBJECTIVES

To assess the effects of daily oral iron supplements for pregnant women, either alone or in conjunction with folic acid, or with other vitamins and minerals as a public health intervention in antenatal care.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (10 January 2015). We also searched the WHO International Clinical Trials Registry Platform (ICTRP) (26 February 2015) and contacted relevant organisations for the identification of ongoing and unpublished studies (26 February 2015) .

SELECTION CRITERIA

Randomised or quasi-randomised trials evaluating the effects of oral preventive supplementation with daily iron, iron + folic acid or iron + other vitamins and minerals during pregnancy.

DATA COLLECTION AND ANALYSIS

We assessed the methodological quality of trials using standard Cochrane criteria. Two review authors independently assessed trial eligibility, extracted data and conducted checks for accuracy. We used the GRADE approach to assess the quality of the evidence for primary outcomes.We anticipated high heterogeneity among trials and we pooled trial results using a random-effects model and were cautious in our interpretation of the pooled results: the random-effects model gives the average treatment effect.

MAIN RESULTS

We included 61 trials. Forty-four trials, involving 43,274 women, contributed data and compared the effects of daily oral supplements containing iron versus no iron or placebo.Preventive iron supplementation reduced maternal anaemia at term by 70% (risk ratio (RR) 0.30; 95% confidence interval (CI) 0.19 to 0.46, 14 trials, 2199 women, low quality evidence), iron-deficiency anaemia at term (RR 0.33; 95% CI 0.16 to 0.69, six trials, 1088 women), and iron deficiency at term by 57% (RR 0.43; 95% CI 0.27 to 0.66, seven trials, 1256 women, low quality evidence). There were no clear differences between groups for severe anaemia in the second or third trimester, or maternal infection during pregnancy (RR 0.22; 95% CI 0.01 to 3.20, nine trials, 2125 women, very low quality evidence; and, RR 1.21; 95% CI 0.33 to 4.46; one trial, 727 women, low quality evidence, respectively), or maternal mortality (RR 0.33; 95% CI 0.01 to 8.19, two trials, 12,560 women, very low quality evidence), or reporting of side effects (RR 1.29; 95% CI 0.83 to 2.02, 11 trials, 2423 women, very low quality evidence). Women receiving iron were on average more likely to have higher haemoglobin (Hb) concentrations at term and in the postpartum period, but were at increased risk of Hb concentrations greater than 130 g/L during pregnancy, and at term.Compared with controls, women taking iron supplements less frequently had low birthweight newborns (8.4% versus 10.3%, average RR 0.84; 95% CI 0.69 to 1.03, 11 trials, 17,613 women, low quality evidence), and preterm babies (RR 0.93; 95% CI 0.84 to 1.03, 13 trials, 19,286 women, moderate quality evidence). They appeared to also deliver slightly heavier babies (mean difference (MD) 23.75; 95% CI -3.02 to 50.51, 15 trials, 18,590 women, moderate quality evidence). None of these results were statistically significant. There were no clear differences between groups for neonatal death (RR 0.91; 95% CI 0.71 to 1.18, four trials, 16,603 infants, low quality evidence), or congenital anomalies (RR 0.88, 95% CI 0.58 to 1.33, four trials, 14,636 infants, low quality evidence).Twenty-three studies were conducted in countries that in 2011 had some malaria risk in parts of the country. In some of these countries/territories, malaria is present only in certain areas or up to a particular altitude. Only two of these studies reported malaria outcomes. There is no evidence that iron supplementation increases placental malaria. For some outcomes heterogeneity was higher than 50%.

AUTHORS' CONCLUSIONS

Supplementation reduces the risk of maternal anaemia and iron deficiency in pregnancy but the positive effect on other maternal and infant outcomes is less clear. Implementation of iron supplementation recommendations may produce heterogeneous results depending on the populations' background risk for low birthweight and anaemia, as well as the level of adherence to the intervention.

Routine iron supplementation and screening for iron deficiency anemia in pregnancy: a systematic review for the U.S. Preventive Services Task Force

BACKGROUND

Routine screening and supplementation for iron deficiency anemia (IDA) in asymptomatic, nonanemic pregnant women could improve maternal and infant health outcomes.

PURPOSE

Update of a 2006 systematic review by the U.S. Preventive Services Task Force on screening and supplementation for IDA in pregnancy.

DATA SOURCES

MEDLINE and the Cochrane Library (1996 to August 2014) and reference lists of relevant systematic reviews to identify studies published since 1996.

STUDY SELECTION

English-language trials and controlled observational studies about effectiveness of screening and routine supplementation for IDA in developed countries.

DATA EXTRACTION

Data extraction and quality assessment confirmed and dual-rated by a second investigator using prespecified criteria.

DATA SYNTHESIS

No study directly compared clinical outcomes or harms of screening or not screening pregnant women for IDA. Twelve supplementation trials were included, and no controlled observational studies met inclusion criteria. On the basis of 11 trials, routine maternal iron supplementation had inconsistent effects on rates of cesarean delivery, small size for gestational age, and low birthweight and no effect on maternal quality of life, gestational age, Apgar scores, preterm birth, or infant mortality. Twelve trials reported improvements in maternal hematologic indices, although not all were statistically significant. Pooled analysis of 4 trials resulted in a statistically significant difference in IDA incidence at term, favoring supplementation (risk ratio, 0.29 [95% CI, 0.17 to 0.49]; I2 = 0%). Maternal iron supplementation did not affect infant iron status at 6 months. Harms, none of which were serious or had long-term consequences, were inconsistently reported in 10 of the trials, with most finding no difference between groups.

LIMITATIONS

Data from trials in countries with limited generalizability to U.S. populations were included. Studies were methodologically heterogeneous, and some were small and underpowered.

CONCLUSION

There is inconclusive evidence that routine prenatal supplementation for IDA improves maternal or infant clinical health outcomes, but supplementation may improve maternal hematologic indices.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality.

Daily oral iron supplementation during pregnancy

BACKGROUND

Iron and folic acid supplementation has been the preferred intervention to improve iron stores and prevent anaemia among pregnant women, and it may also improve other maternal and birth outcomes.

OBJECTIVES

To assess the effects of daily oral iron supplements for pregnant women, either alone or in conjunction with folic acid, or with other vitamins and minerals as a public health intervention.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (2 July 2012). We also searched the WHO International Clinical Trials Registry Platform (ICTRP) (2 July 2012) and contacted relevant organisations for the identification of ongoing and unpublished studies.

SELECTION CRITERIA

Randomised or quasi-randomised trials evaluating the effects of oral preventive supplementation with daily iron, iron + folic acid or iron + other vitamins and minerals during pregnancy.

DATA COLLECTION AND ANALYSIS

We assessed the methodological quality of trials using standard Cochrane criteria. Two review authors independently assessed trial eligibility, extracted data and conducted checks for accuracy.

MAIN RESULTS

We included 60 trials. Forty-three trials, involving more than 27,402 women, contributed data and compared the effects of daily oral supplements containing iron versus no iron or placebo.Overall, women taking iron supplements were less likely to have low birthweight newborns (below 2500 g) compared with controls (8.4% versus 10.2%, average risk ratio (RR) 0.81; 95% confidence interval (CI) 0.68 to 0.97, 11 trials, 8480 women) and mean birthweight was 30.81 g greater for those infants whose mothers received iron during pregnancy (average mean difference (MD) 30.81; 95% CI 5.94 to 55.68, 14 trials, 9385 women). Preventive iron supplementation reduced the risk of maternal anaemia at term by 70% (RR 0.30; 95% CI 0.19 to 0.46, 14 trials, 2199 women) and iron deficiency at term by 57% (RR 0.43; 95% CI 0.27 to 0.66, seven trials, 1256 women). Although the difference between groups did not reach statistical significance, women who received iron supplements were more likely than controls to report side effects (25.3% versus 9.91%) (RR 2.36; 95% CI 0.96 to 5.82, 11 trials, 4418 women), particularly at doses 60 mg of elemental iron or higher. Women receiving iron were on average more likely to have higher haemoglobin (Hb) concentrations at term and in the postpartum period, but were at increased risk of Hb concentrations greater than 130g/L during pregnancy and at term. Twenty-three studies were conducted in countries that in 2011 had some malaria risk in parts of the country. In some of these countries/territories, malaria is present only in certain areas or up to a particular altitude. Only two of these reported malaria outcomes. There is no evidence that iron supplementation increases placental malaria. For some outcomes heterogeneity was higher than 50%.

AUTHORS' CONCLUSIONS

Prenatal supplementation with daily iron are effective to reduce the risk of low birthweight, and to prevent maternal anaemia and iron deficiency in pregnancy. Associated maternal side effects and particularly high Hb concentrations during pregnancy at currently used doses suggest the need to update recommendations on doses and regimens for routine iron supplementation.