What is the recommended treatment for iron deficiency anemia during pregnancy using iron infusion?

Iron Infusion During Pregnancy for Iron Deficiency Anemia

Oral iron therapy (60-120 mg/day) should be used as first-line treatment for iron deficiency anemia during pregnancy, with intravenous iron infusion reserved for cases of severe anemia (Hb <9.0 g/dL), oral iron intolerance, lack of response to oral therapy, or when rapid correction is needed in advanced pregnancy. 1, 2

Diagnostic Approach

• Screen for anemia at first prenatal visit using hemoglobin/hematocrit and serum ferritin
• Iron deficiency anemia diagnosis:
  • Low hemoglobin (based on trimester-specific values)
  • Serum ferritin <30 μg/L (definitive iron deficiency)
  • Ferritin 30-100 μg/L with transferrin saturation <20% may indicate iron deficiency with inflammation 2

Treatment Algorithm

First-Line Treatment

• Oral iron therapy:
  • Dosage: 60-120 mg elemental iron daily 1
  • Formulations: ferrous sulfate 200 mg (65 mg elemental iron), ferrous gluconate, or ferrous fumarate 2
  • Administration: Once-daily morning dosing preferred
  • Duration: Continue until hemoglobin normalizes, then reduce to 30 mg/day 1
  • Enhancement: Take with vitamin C to improve absorption 2
  • Avoid taking with tea, coffee, calcium, or antacids (reduce absorption) 2

Second-Line Treatment (Intravenous Iron)

Indications for IV iron infusion:

• Severe anemia (Hb <9.0 g/dL) 1
• Intolerance to oral iron preparations (significant gastrointestinal side effects)
• Non-compliance with oral therapy
• Lack of response to oral iron despite compliance (no Hb increase of 1 g/dL after 4 weeks)
• Conditions affecting iron absorption
• Need for rapid correction of anemia (e.g., advanced pregnancy) 2, 3

Monitoring and Follow-up

• Check hemoglobin after 4 weeks of treatment
• Expected response: Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks 2
• If no response (Hb increase <1 g/dL) after 4 weeks despite compliance, consider:
  1. Further evaluation with MCV, RDW, serum ferritin
  2. Switching to IV iron therapy
  3. Evaluating for other causes of anemia (thalassemia, sickle cell trait) 1, 2

Specific IV Iron Considerations in Pregnancy

• Iron sucrose has been studied in pregnancy and appears safe after the first trimester 4, 5
• Ferric carboxymaltose has been studied in pregnancy and is preferred by some guidelines 3
• Ferumoxytol may allow complete replacement with fewer infusions (1-2 visits vs 4-7 with iron sucrose) 6
• Close monitoring during administration is recommended for all IV iron products due to risk of adverse reactions 3

Safety Considerations

• Oral iron: Common side effects include gastrointestinal symptoms (constipation, nausea, abdominal pain)
  • Consider alternate-day dosing if daily dosing causes GI side effects 2
  • Liquid preparations if tablets not tolerated 2
• IV iron:
  • Potential for serious adverse effects including allergic reactions
  • Rare cases of rhabdomyolysis have been reported 7
  • FDA notes that iron sucrose has been used after first trimester without evidence of adverse maternal or fetal outcomes 4

Clinical Pitfalls to Avoid

• Failing to distinguish between physiologic anemia of pregnancy and true iron deficiency anemia
• Not recognizing non-response to oral iron after 4 weeks of therapy
• Overlooking potential causes of iron malabsorption
• Delaying IV iron when indicated, particularly in advanced pregnancy when time to delivery is limited
• Not monitoring for adverse reactions during IV iron administration

Remember that untreated iron deficiency anemia in pregnancy is associated with adverse maternal outcomes such as postpartum anemia and adverse pregnancy outcomes including increased risk for preterm delivery and low birth weight 4.