What is the recommended management for anemia in pregnancy, including oral iron dosing, criteria for switching to intravenous iron, and appropriate intravenous iron dosing regimens?

Management of Anemia in Pregnancy and Iron Infusion Protocols

For pregnant women with iron deficiency anemia, start with oral iron at 60-120 mg elemental iron daily, reassess after 4 weeks, and switch to intravenous iron if there is no response (hemoglobin increase <1 g/dL), intolerance, or severe anemia requiring rapid correction. 1, 2

Initial Screening and Diagnosis

• Screen all pregnant women for anemia at the first prenatal visit and again at 24-28 weeks gestation using hemoglobin or hematocrit testing 2
• Anemia is defined as hemoglobin <11.0 g/dL in the first trimester and <10.5 g/dL in the second and third trimesters 3
• Make a presumptive diagnosis of iron deficiency anemia and begin treatment immediately without waiting for confirmatory testing in non-acutely ill pregnant women 2, 4
• Confirm the diagnosis with repeat hemoglobin or hematocrit before initiating treatment if screening is positive 2

Oral Iron Therapy: First-Line Treatment

Prescribe 60-120 mg/day of elemental iron orally as first-line treatment for mild to moderate anemia. 2, 4

• All pregnant women should receive at least 30 mg/day of oral elemental iron starting at the first prenatal visit as routine supplementation 2
• For diagnosed anemia, increase to therapeutic dosing of 60-120 mg elemental iron daily 2, 4
• Taking iron with ascorbic acid (vitamin C) may enhance absorption, though evidence is limited 4
• Counsel patients that taking iron with food or using enteric-coated formulations improves tolerability but decreases absorption 4
• Provide dietary counseling on iron-rich foods including meat, poultry, fruits, vegetables, and iron-fortified grain products 2, 4

Common Pitfalls with Oral Iron

• Gastrointestinal side effects occur frequently and lead to poor compliance—verify that patients are actually taking the medication 4, 5
• New evidence suggests intermittent dosing (alternate days) is as effective as daily dosing with fewer side effects 3
• Vegetarian women may require nearly double the iron supplementation due to lower absorption of non-heme iron 2

Monitoring Response to Oral Iron

• Reassess hemoglobin or hematocrit after 4 weeks of treatment 2, 4
• Expected response is an increase of ≥1 g/dL in hemoglobin or ≥3% in hematocrit 2, 4
• If no response occurs after 4 weeks despite confirmed compliance and absence of acute illness, perform additional testing including mean corpuscular volume (MCV), red cell distribution width (RDW), and serum ferritin 1, 2, 4
• Consider alternative diagnoses in women of African, Mediterranean, or Southeast Asian ancestry, where thalassemia minor or sickle cell trait may present as mild anemia unresponsive to oral iron 1

Criteria for Switching to Intravenous Iron

Switch to intravenous iron therapy if any of the following criteria are met: 1, 2

• Failure to respond to oral iron after 4 weeks of confirmed compliance
• Intolerance to oral iron preparations due to gastrointestinal side effects
• Inability to absorb oral iron (celiac disease, post-bariatric surgery, inflammatory bowel disease)
• Severe anemia with hemoglobin <9.0 g/dL requiring rapid correction
• Ongoing blood loss
• Second or third trimester of pregnancy when rapid correction is needed 6

Intravenous Iron Therapy: Preferred Agents and Dosing

Ferric carboxymaltose (Injectafer) is the preferred intravenous iron preparation based on clinical trial evidence in pregnancy and postpartum populations. 1

Ferric Carboxymaltose Dosing Protocol

• Dose: 15 mg/kg body weight up to a maximum of 750 mg per dose 1
• Administer on two occasions separated by at least 7 days 1
• Cumulative maximum dose: 1,500 mg 1
• Administration time: 15-minute infusion, which is significantly more convenient than older preparations 1

Alternative Intravenous Iron Preparations

• Iron sucrose (Venofer): Maximum dose of 200 mg per dose with a 10-minute infusion 1
• Iron dextran (Cosmofer): Can give total dose in a single 6-hour infusion but carries a 0.6-0.7% risk of serious reactions including anaphylaxis 1
• Contemporary formulations have rare allergic reactions and offer better safety profiles than older preparations 3, 5

Monitoring Response to Intravenous Iron

• Reassess hemoglobin and ferritin at appropriate intervals to confirm response 1
• Expected response: Hemoglobin should increase by ≥1 g/dL within 2-4 weeks 1
• Intravenous iron leads to more rapid hemoglobin recovery compared to oral iron, particularly in the postpartum period 7

Dose Adjustment After Correction

• Once hemoglobin normalizes for gestational age, decrease to maintenance dose of 30 mg/day oral iron 1, 2
• If hemoglobin is >15.0 g/dL or hematocrit is >45.0% in the second or third trimester, evaluate for poor blood volume expansion and potential pregnancy complications 2

When to Refer for Specialist Evaluation

• Refer to a physician familiar with anemia in pregnancy if hemoglobin is <9.0 g/dL or hematocrit is <27.0% 4
• Blood transfusion is not indicated in stable pregnant patients with hemoglobin around 9 g/dL without active bleeding or hemodynamic instability 2

Postpartum Management

• Screen women at risk for anemia at 4-6 weeks postpartum using hemoglobin or hematocrit 2
• Risk factors include anemia persisting through the third trimester, excessive blood loss at delivery, and multiple birth 2
• Hemoglobin <10 g/dL in the postpartum period indicates clinically significant anemia requiring treatment 8
• Continue iron supplementation throughout pregnancy and the postpartum period to prevent recurrence 2
• For postpartum hemoglobin values less than 9.5 g/dL, intravenous iron carboxymaltose is preferable to oral iron for more rapid hemoglobin recovery 7