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
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.
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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/
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- Iron deficiency and iron deficiency anemia are common during pregnancy and are associated with adverse outcomes
- Symptoms are often dismissed as normal during pregnancy
- Ferritin and hemoglobin should be routinely assessed at the initial and 28-week prenatal visits5
- Oral iron is the first-line treatment
- Parenteral iron is safe and effective from the second trimester onward
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