What is the recommended treatment for iron‑deficiency anemia in a pregnant woman in the first trimester?

Treatment of Iron-Deficiency Anemia in the First Trimester

Start oral iron supplementation at 60–120 mg of elemental iron daily immediately upon diagnosis of anemia in the first trimester, without waiting for confirmatory iron studies. 1, 2, 3

Diagnostic Confirmation

• Confirm anemia by repeating hemoglobin or hematocrit before initiating treatment; in the first trimester, anemia is defined as hemoglobin < 11.0 g/dL. 1, 3
• In stable, non-acutely ill pregnant women, make a presumptive diagnosis of iron-deficiency anemia and begin treatment immediately without awaiting additional laboratory tests such as ferritin or transferrin saturation. 1, 3
• Refer to a physician experienced in pregnancy-related anemia if hemoglobin falls below 9.0 g/dL or hematocrit below 27%, as this represents severe anemia requiring specialized evaluation. 1, 3

First-Line Therapeutic Regimen

• Prescribe 60–120 mg of elemental iron daily (e.g., ferrous sulfate 325 mg once daily, which provides approximately 65 mg elemental iron) as the therapeutic dose for confirmed anemia. 1, 2, 3
• This therapeutic dose is distinct from and higher than the universal prophylactic dose of 30 mg daily recommended for all pregnant women starting at the first prenatal visit. 1, 2, 3
• Counsel patients to consume iron-rich foods (red meat, poultry, fish, legumes, fortified cereals) and foods that enhance absorption (vitamin C-rich fruits and vegetables). 1, 3

Monitoring Treatment Response

• Recheck hemoglobin or hematocrit after 4 weeks of oral iron therapy to assess treatment effectiveness. 1, 3
• An adequate response is defined as an increase of ≥ 1 g/dL in hemoglobin or ≥ 3% in hematocrit after the 4-week interval. 1, 3
• If anemia persists after 4 weeks despite confirmed adherence and absence of acute illness, obtain additional laboratory studies including mean corpuscular volume (MCV), red cell distribution width (RDW), and serum ferritin to evaluate for iron-refractory anemia. 1, 3

Management of Iron-Refractory Anemia

• In women of African, Mediterranean, or Southeast Asian ancestry whose anemia does not respond to adequate oral iron, consider underlying hemoglobinopathies such as thalassemia minor or sickle cell trait. 1, 3
• Before switching to intravenous iron, confirm compliance with the oral regimen and rule out other causes of treatment failure, as gastrointestinal side effects (nausea, constipation, diarrhea) frequently lead to poor adherence. 2, 4
• If intravenous iron is indicated, ferric carboxymaltose is the preferred formulation due to rapid effectiveness and better tolerability, though experience in the first trimester is limited. 4, 5

Dose Adjustment After Normalization

• Once hemoglobin normalizes to ≥ 11.0 g/dL (first-trimester threshold), reduce oral iron to the prophylactic dose of 30 mg elemental iron daily for the remainder of pregnancy. 1, 3
• Continue iron supplementation throughout pregnancy and into the postpartum period to maintain adequate iron stores and prevent recurrence. 3, 4

Common Pitfalls to Avoid

• Do not use the prophylactic 30 mg/day dose to treat confirmed anemia; the therapeutic dose of 60–120 mg/day is required for adequate hemoglobin repletion. 1, 2, 3
• Do not postpone iron therapy while awaiting confirmatory laboratory tests in stable pregnant women with mild-to-moderate anemia. 1, 3
• Do not overlook evaluation for hemoglobinopathies when anemia remains refractory after 4 weeks in ethnically at-risk populations. 1, 3
• Do not discontinue iron supplementation once hemoglobin normalizes; instead, reduce to prophylactic dosing but continue throughout pregnancy. 3, 4

Postpartum Follow-Up

• Screen for anemia at 4–6 weeks postpartum using hemoglobin or hematocrit in women who had anemia during pregnancy. 1, 3
• Risk factors for postpartum anemia include persistent anemia through the third trimester, excessive peripartum blood loss, and multiple gestation. 1, 3