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Open Access

Iron deficiency and iron deficiency anemia in pregnancy

A. Kinga Malinowski and Ally Murji
CMAJ July 26, 2021 193 (29) E1137-E1138; DOI: https://doi.org/10.1503/cmaj.210007
A. Kinga Malinowski
Department of Obstetrics & Gynaecology (Malinowski, Murji), Sinai Health System; University of Toronto (Malinowski, Murji), Toronto, Ont.
MD MSc
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Ally Murji
Department of Obstetrics & Gynaecology (Malinowski, Murji), Sinai Health System; University of Toronto (Malinowski, Murji), Toronto, Ont.
MD MPH
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Iron deficiency and iron deficiency anemia are common during pregnancy and are associated with adverse outcomes

Prenatal iron deficiency occurs in more than 30% of pregnancies in Canada.1 It has been linked with low birth weight, small for gestational age size, preterm birth, need for blood transfusion for the mother, postpartum hemorrhage2,3 and long-term neurocognitive effects in childhood.4

Symptoms are often dismissed as normal during pregnancy

Symptoms include fatigue, weakness, dizziness, irritability, decreased stamina, hair loss and dyspnea, all of which are often attributed to the physiologic changes of pregnancy. Consequently, many patients go untreated, which increases maternal, fetal and neonatal health risks.3,5

Ferritin and hemoglobin should be routinely assessed at the initial and 28-week prenatal visits5

Ferritin < 30 ug/L is diagnostic for iron deficiency. Higher ferritin values in patients with inflammation or infection do not exclude iron deficiency.5 Anemia during pregnancy is diagnosed when the patient’s hemoglobin level is < 110 g/L6 (with some suggesting hemoglobin < 105 g/L in the second trimester);2 postpartum, it is diagnosed at hemoglobin levels < 100 g/L.5

Oral iron is the first-line treatment

Oral ferrous iron medications should contain 40–100 mg of elemental iron5,7 and be taken daily or every other day to mitigate adverse effects (Table 1).5 Enteric-coated or sustained-release products are not as well absorbed (i.e., onset of action is distal to the duodenum). 5 To maximize absorption, patients should take oral iron with vitamin C (250–500 mg) on an empty stomach if tolerated, 1 hour before or 2 hours after calcium, proton pump inhibitors, antacids, thyroxine, tea, coffee, milk, soy and eggs.8 Response to oral iron should be evaluated by measuring the hemoglobin level 2–4 weeks after treatment begins.5,7 Treatment should continue for at least 3 months after the hemoglobin level normalizes until 6 weeks postpartum.5,7

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Table 1:

Oral and parenteral iron preparations*

Parenteral iron is safe and effective from the second trimester onward

Parenteral iron rapidly achieves the target hemoglobin with few adverse effects, and should be considered after the first trimester for patients with intolerance to oral therapy; a poor response (hemoglobin increase of < 10 g/L 2 wk after starting treatment or < 20 g/L after 4 wk); moderate-to-severe iron deficiency anemia (hemoglobin < 80 g/L); or iron deficiency anemia occuring within 4–6 weeks of anticipated delivery.7 A hematologist should be consulted if the patient has a hemoglobinopathy, such as thalassemia or sickle cell disease.

CMAJ invites submissions to “Five things to know about …” Submit manuscripts online at http://mc.manuscriptcentral.com/cmaj

Footnotes

  • Competing interests: A. Kinga Malinowski reports consulting and speaker fees for Pfizer and Alexion. Ally Murji reports consulting and speaker fees from Abbvie, Bayer and Pfizer.

  • This article has been peer reviewed.

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY-NC-ND 4.0) licence, which permits use, distribution and reproduction in any medium, provided that the original publication is properly cited, the use is noncommercial (i.e., research or educational use), and no modifications or adaptations are made. See: https://creativecommons.org/licenses/by-nc-nd/4.0/

References

  1. ↵
    1. Tang G,
    2. Lausman A,
    3. Abdulrehman J,
    4. et al
    . Prevalence of iron deficiency and iron deficiency anemia during pregnancy: a single centre Canadian study. Blood 2019;134(Suppl 1):3389.
    OpenUrl
  2. ↵
    1. Young MF,
    2. Oaks BM,
    3. Tandon S,
    4. et al
    . Maternal hemoglobin concentrations across pregnancy and maternal and child health: a systematic review and meta-analysis. Ann N Y Acad Sci 2019; 1450: 47–68.
    OpenUrl
  3. ↵
    1. Peña-Rosas JP,
    2. De-Regil LM,
    3. Dowswell T,
    4. et al
    . Daily oral iron supplementation during pregnancy. Cochrane Database Syst Rev 2012;12:CD004736.
    OpenUrlPubMed
  4. ↵
    1. Georgieff MK
    . Iron deficiency in pregnancy. Am J Obstet Gynecol 2020;223:516–24.
    OpenUrl
  5. ↵
    1. Pavord S,
    2. Daru J,
    3. Prasannan N,
    4. et al
    . UK guidelines on the management of iron deficiency in pregnancy. Br J Haematol 2020;188:819–30.
    OpenUrl
  6. ↵
    Haemoglobin concentrations for the diagnosis of anaemia and assessment of severity. Vitamin and Mineral Nutrition Information System (WHO/NMH/NHD/MNM/11.1). Geneva: World Health Organization; 2011. Available: https://www.who.int/vmnis/indicators/haemoglobin.pdf (accessed 2021 Jan. 3).
  7. ↵
    1. Muñoz M,
    2. Pena-Rosas JP,
    3. Robinson S,
    4. et al
    . Patient blood management in obstetrics: management of anaemia and haematinic deficiencies in pregnancy and in the post-partum period: NATA consensus statement. Transfus Med 2018;28: 22–39.
    OpenUrlCrossRefPubMed
  8. ↵
    1. Auerbach M
    . Patient education: Anemia caused by low iron in adults (beyond the basics). UpToDate; 2021 [updated 2021 Feb. 21].
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Canadian Medical Association Journal: 193 (29)
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Vol. 193, Issue 29
26 Jul 2021
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Iron deficiency and iron deficiency anemia in pregnancy
A. Kinga Malinowski, Ally Murji
CMAJ Jul 2021, 193 (29) E1137-E1138; DOI: 10.1503/cmaj.210007

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Iron deficiency and iron deficiency anemia in pregnancy
A. Kinga Malinowski, Ally Murji
CMAJ Jul 2021, 193 (29) E1137-E1138; DOI: 10.1503/cmaj.210007
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