How should iron deficiency anemia be screened, diagnosed, and managed (including oral and intravenous iron dosing and monitoring) in pregnant women?

Management of Iron Deficiency Anemia in Pregnant Women

Screening Protocol

Screen all pregnant women for anemia at the first prenatal visit and again at 24-28 weeks gestation using hemoglobin or hematocrit. 1

• First trimester anemia: hemoglobin <11.0 g/dL 1, 2
• Second/third trimester anemia: hemoglobin <10.5 g/dL 1, 3
• If screening is positive, confirm with repeat testing before initiating treatment 1
• However, in non-acutely ill pregnant women, make a presumptive diagnosis of iron deficiency anemia and begin treatment immediately without waiting for additional confirmatory tests 1, 2

Universal Prophylaxis for All Pregnant Women

All pregnant women should start 30 mg elemental iron daily at the first prenatal visit and continue throughout pregnancy and postpartum, regardless of baseline hemoglobin. 1

• This addresses the three-fold rise in iron requirements during second and third trimesters (≈5 mg elemental iron per day) that cannot be met by diet alone 1
• Do not delay prophylactic iron until anemia develops 1

Treatment of Confirmed Anemia

Mild to Moderate Anemia (Hemoglobin ≥9.0 g/dL)

Prescribe 60-120 mg elemental iron daily as therapeutic dosing—this is higher than the 30 mg prophylactic dose. 1, 2

• Take on an empty stomach to maximize absorption 2
• Consider taking with vitamin C (ascorbic acid) to enhance absorption, though evidence is limited 2
• Avoid taking with food, antacids, or proton pump inhibitors as they decrease absorption 2
• Counsel patients on iron-rich foods: meat, poultry, iron-fortified grains 1, 2
• Vegetarian women may require nearly double the supplementation due to lower absorption of non-heme iron 1

Severe Anemia (Hemoglobin <9.0 g/dL or Hematocrit <27%)

Refer immediately to a physician experienced in pregnancy-related anemia management. 1, 2

Monitoring Treatment Response

Reassess hemoglobin or hematocrit after 4 weeks of oral iron therapy. 1, 2

• Expected response: increase of ≥1 g/dL in hemoglobin OR ≥3% in hematocrit 1, 2
• If response criteria are met, continue iron supplementation until values normalize for gestational age 1

Management of Non-Response After 4 Weeks

If no response occurs despite confirmed compliance and absence of acute illness, perform additional testing: 1, 2

• Mean corpuscular volume (MCV) 1, 2
• Red cell distribution width (RDW) 1, 2
• Serum ferritin 1, 2

In women of African, Mediterranean, or Southeast Asian ancestry, evaluate for hemoglobinopathies (thalassemia minor, sickle-cell trait) as causes of iron-refractory anemia. 1

Critical pitfall: Verify medication adherence before labeling therapy as failed—gastrointestinal side effects (nausea, constipation, diarrhea) frequently lead to discontinuation 1, 2

Intravenous Iron Therapy Indications

Consider intravenous iron for: 1, 2

• Severe anemia (hemoglobin <9.0 g/dL) 1
• Intolerance to oral iron 1, 2
• Lack of response to oral iron after 4 weeks despite confirmed compliance 1, 2
• Need for rapid correction of anemia 2
• Impaired absorption (celiac disease, post-bariatric surgery) 4
• Second and third trimesters when rapid repletion is needed 4

Ferric carboxymaltose is the preferred intravenous iron formulation due to rapid effectiveness and better tolerability. 1

• Before switching to IV iron, confirm compliance with oral regimen and rule out other causes of iron-refractory anemia 1
• Anaphylactic reactions are extremely rare with non-dextran products, but close surveillance during administration is recommended 5

Dose Adjustment After Normalization

Once hemoglobin or hematocrit normalizes for gestational age, reduce oral iron to the prophylactic dose of 30 mg elemental iron daily for the remainder of pregnancy. 1

• Warning: If hemoglobin rises above 15.0 g/dL or hematocrit exceeds 45% in the second or third trimester, evaluate for poor blood volume expansion and potential pregnancy complications 1

Postpartum Management

Screen women at risk for anemia at 4-6 weeks postpartum using hemoglobin or hematocrit. 1

• Risk factors: anemia persisting through third trimester, excessive blood loss at delivery, multiple birth 1
• Continue iron supplementation throughout pregnancy and postpartum period to prevent recurrence 1

Common Pitfalls to Avoid

• Do not postpone iron therapy while awaiting confirmatory tests in women with mild-to-moderate anemia who are not severely ill 1
• Do not use the prophylactic 30 mg/day dose to treat confirmed anemia—the therapeutic dose of 60-120 mg/day is required 1
• Do not overlook evaluation for hemoglobinopathies in ethnically at-risk women when anemia remains refractory to oral iron 1
• Do not assume compliance—verify that patients are actually taking medication, as side effects frequently lead to discontinuation 1, 2
• Do not attribute iron deficiency anemia solely to aspirin or proton pump inhibitors without completing appropriate investigations 2

Maternal-Fetal Outcomes

Untreated iron deficiency anemia during pregnancy is associated with increased risk of preterm birth, low birth weight, and postpartum anemia. 1

• Blood transfusion is not indicated in stable pregnant patients with hemoglobin around 9 g/dL without active bleeding or hemodynamic instability 1