Revisiting the basis for haemoglobin screening in pregnancy

Iron Deficiency Anemia in Pregnancy

Anemia is defined as a low red blood cell count, a low hematocrit, or a low hemoglobin concentration. In pregnancy, a hemoglobin concentration of less than 11.0 g/dL in the first trimester and less than 10.5 or 11.0 g/dL in the second or third trimester (depending on the guideline used) is considered anemia. Anemia is the most common hematologic abnormality in pregnancy. Maternal anemia is associated with adverse fetal, neonatal and childhood outcomes, but causality is not established. Maternal anemia increases the likelihood of transfusion at delivery. Besides hemodilution, iron deficiency is the most common cause of anemia in pregnancy. The American College of Obstetricians and Gynecologists recommends screening for anemia with a complete blood count in the first trimester and again at 24 0/7 to 28 6/7 weeks of gestation. Mild anemia, with a hemoglobin of 10.0 g/dL or higher and a mildly low or normal mean corpuscular volume (MCV) is likely iron deficiency anemia. A trial of oral iron can be both diagnostic and therapeutic. Mild anemia with a very low MCV, macrocytic anemia, moderate anemia (hemoglobin 7.0-9.9 g/dL) or severe anemia (hemoglobin 4.0-6.9 g/dL) requires further investigation. Once a diagnosis of iron deficiency anemia is confirmed, first-line treatment is oral iron. New evidence suggests that intermittent dosing is as effective as daily or twice-daily dosing with fewer side effects. For patients with iron deficiency anemia who cannot tolerate, cannot absorb, or do not respond to oral iron, intravenous iron is preferred. With contemporary formulations, allergic reactions are rare.

Iron preparations for women of reproductive age with iron deficiency anaemia in pregnancy (FRIDA): a systematic review and network meta-analysis

BACKGROUND

Numerous iron preparations are available for the treatment of iron deficiency anaemia in pregnancy. We aimed to provide a summary of the effectiveness and safety of iron preparations used in this setting.

METHODS

We did a systematic review and network meta-analysis of randomised trials. We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, trial registers, and grey literature for trials published in any language from Jan 1, 2011, to Feb 28, 2021. We included trials including pregnant women with iron deficiency anaemia and evaluating iron preparations, irrespective of administration route, with at least 60 mg of elemental iron, in comparison with another iron or non-iron preparation. Three authors independently selected studies, extracted data, and did a risk of bias assessment using the Cochrane tool (version 1.0). The primary outcome was the effectiveness of iron preparations, evaluated by changes in haemoglobin concentration at 4 weeks from baseline. The secondary outcomes were change in serum ferritin concentration at 4 weeks from baseline and treatment-related severe and non-severe adverse events. We did random-effects pairwise and network meta-analyses. Side-effects were reported descriptively for each trial. This study is registered with PROSPERO, CRD42018100822.

FINDINGS

Among 3037 records screened, 128 full-text articles were further assessed for eligibility. Of the 53 eligible trials (reporting on 9145 women), 30 (15 interventions; 3243 women) contributed data to the network meta-analysis for haemoglobin and 15 (nine interventions; 1396 women) for serum ferritin. The risk of bias varied across the trials contributing to network meta-analysis, with 22 of 30 trials in the network meta-analysis for haemoglobin judged to have a high or medium global risk of bias. Compared with oral ferrous sulfate, intravenous iron sucrose improved both haemoglobin (mean difference 7·17 g/L, 95% CI 2·62-11·73; seven trials) and serum ferritin (mean difference 49·66 μg/L, 13·63-85·69; four trials), and intravenous ferric carboxymaltose improved haemoglobin (mean difference 8·52 g/L, 0·51-16·53; one trial). The evidence for other interventions compared with ferrous sulfate was insufficient. The most common side-effects with oral iron preparations were gastrointestinal effects (nausea, vomiting, and altered bowel movements). Side-effects were less common with parenteral iron preparations, although these included local pain, skin irratation, and, on rare occasions, allergic reactions.

INTERPRETATION

Iron preparations for treatment of iron deficiency anaemia in pregnancy vary in effectiveness, with good evidence of benefit for intravenous iron sucrose and some evidence for intravenous ferric carboxymaltose. Clinicians and policy makers should consider the effectiveness of individual preparations before administration, to ensure effective treatment.

FUNDING

None.

Iron deficiency anaemia in pregnancy: A contemporary review

Iron deficiency anaemia is a global health problem, which particularly affects pregnant women. Iron deficiency anaemia during pregnancy is associated with increased maternal and perinatal morbidity and mortality. Maternal iron deficiency may also be associated with neurocognitive deficits in infants. Iron requirements increase during pregnancy and are influenced by hepcidin, the master regulator of iron homeostasis. The enduring global burden of maternal anaemia suggests that currently employed iron supplementation strategies are suboptimal. Recent developments in our understanding of systemic and placental iron homeostasis may improve therapeutic effectiveness by altering the dose and frequency of oral iron. Intravenous iron appears to be a safe treatment to correct maternal anaemia rapidly but research on patient-centred outcomes and cost-effectiveness is needed. Future trials should be adequately powered to assess outcomes relevant to pregnant women.

Gestational iron deficiency anemia is associated with preterm birth, fetal growth restriction, and postpartum infections

OBJECTIVES

Gestational IDA has been linked to adverse maternal and neonatal outcomes, but the impact of iron supplementation on outcome measures remains unclear. Our objective was to assess the effects of gestational IDA on pregnancy outcomes and compare outcomes in pregnancies treated with either oral or intravenous iron supplementation.

METHODS

We evaluated maternal and neonatal outcomes in 215 pregnancies complicated with gestational IDA (Hb<100 g/L) and delivered in our tertiary unit between January 2016 and October 2018. All pregnancies from the same period served as a reference group (n=11,545). 163 anemic mothers received oral iron supplementation, and 52 mothers received intravenous iron supplementation.

RESULTS

Gestational IDA was associated with an increased risk of preterm birth (10.2% vs. 6.1%, p=0.009) and fetal growth restriction (FGR) (1.9% vs. 0.3%, p=0.006). The gestational IDA group that received intravenous iron supplementation had a greater increase in Hb levels compared to those who received oral medication (18.0 g/L vs. 10.0 g/L, p<0.001), but no statistically significant differences in maternal and neonatal outcomes were detected.

CONCLUSIONS

Compared to the reference group, prematurity, FGR, postpartum infections, and extended hospital stays were more common among mothers with gestational IDA, causing an additional burden on the families and the healthcare system.

Systematic review of guidelines for the diagnosis and treatment of iron deficiency anemia using intravenous iron across multiple indications

OBJECTIVE

To explore current recommendations for intravenous (IV) iron use in clinical guidelines for iron deficiency anemia (IDA) across different therapeutic areas and identify recommendations, if any, for the treatment of IDA.

METHODS

A literature search was conducted in Medline, EMBASE, BIOSIS, Cochrane Collaboration, and on websites of relevant professional associations. Searches were limited to English publications. 1292 citations were identified, 219 papers were assessed, and 35 guidelines were identified for inclusion.

RESULTS

The guidelines covered a variety of geographies: United States (US; n = 10); Europe (n = 11); "Rest-of-World" (n = 9); and "Other" organizations (n = 5). These covered a variety of specialties. Guidelines defined iron deficiency and IDA generally by serum ferritin and transferrin saturation levels. One-fifth of the reviewed guidelines (7 of 35) included no mention or recommendation regarding parenteral iron's utility in the management of IDA. Fifteen guidelines recommended using parenteral iron in the management of IDA. Fewer US guidelines included recommendations around IV iron than in Europe or the rest of the world. Approximately 60% of the guidelines have not been updated in ≥5 years and consequently do not reflect current evidence on the safety and efficacy of IV iron.

CONCLUSIONS

While national and international guidelines for management of IDA exist, many are outdated and do not reflect current evidence including, but not limited to, parenteral iron use. Urgent consideration should be given to updating and clarifying management guidelines for IDA using the latest treatment modalities and options, particularly in the US.