How is anemia managed in pregnancy?

Management of Anemia in Pregnancy

All pregnant women should be screened for anemia at the first prenatal visit and again at 24-28 weeks gestation using hemoglobin or hematocrit testing, with treatment initiated based on severity and response to oral iron. 1

Screening and Diagnosis

• Screen all pregnant women at the first prenatal visit and again at 24-28 weeks gestation using hemoglobin or hematocrit measurement 2, 1

• Anemia is defined as hemoglobin <11.0 g/dL in the first trimester and <10.5-11.0 g/dL in the second or third trimester 3

• If screening is positive, confirm with repeat hemoglobin or hematocrit before initiating treatment 1

• For non-acutely ill pregnant women, the American College of Obstetricians and Gynecologists recommends making a presumptive diagnosis of iron deficiency anemia and beginning treatment immediately without waiting for additional testing 1, 4

• Serum ferritin can be helpful for diagnosis (threshold <30 μg/L indicates iron deficiency), though it has limitations during pregnancy as it decreases in late pregnancy despite adequate iron stores and increases during inflammation 2, 5

Treatment Algorithm by Severity

Universal Prophylaxis

• Start 30 mg/day of oral elemental iron at the first prenatal visit for all pregnant women as recommended by the Centers for Disease Control and Prevention 1

Mild to Moderate Anemia (Hemoglobin 7.0-10.0 g/dL)

• Prescribe 60-120 mg/day of elemental iron orally as first-line treatment 2, 1, 3

• Provide dietary counseling on iron-rich foods including meat, poultry, certain fruits and vegetables, and fortified grain products 2, 1

• Recent evidence suggests intermittent (every other day) dosing is as effective as daily dosing with fewer gastrointestinal side effects 3

• Vegetarian women may require nearly double the iron supplementation due to lower absorption of non-heme iron 1

Monitoring Response to Treatment

• Reassess hemoglobin or hematocrit after 4 weeks of treatment 1, 4

• Expected response is an increase of ≥1 g/dL in hemoglobin or ≥3% in hematocrit 1, 4

• If no response after 4 weeks despite compliance and absence of acute illness, perform additional testing including mean corpuscular volume, red cell distribution width, and serum ferritin 1, 4

Dose Adjustment After Response

• Once hemoglobin or hematocrit normalizes for gestational age, reduce iron dose to 30 mg/day for maintenance 1

• 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 1

Intravenous Iron Therapy

Consider intravenous iron for pregnant women with severe anemia, intolerance to oral iron, or lack of response to oral iron after 4 weeks despite compliance. 1

• Before switching to intravenous iron, confirm compliance with oral iron regimen and rule out other causes of iron-refractory anemia 1

• Ferric carboxymaltose is the preferred intravenous iron option due to its rapid effectiveness and better tolerability 1

• Intravenous iron is safe after the first trimester, with published studies showing no adverse maternal or fetal outcomes 6

• Severe adverse reactions including circulatory failure and severe hypotension may occur with parenteral iron products, which can cause fetal bradycardia, especially during the second and third trimester 6

• Allergic reactions are rare with contemporary formulations 3

• Intravenous iron should be considered for anemia beyond 34 weeks of pregnancy when rapid correction is needed 7

Common Pitfalls and Caveats

• Physiologic hemodilution is normal during pregnancy and should not be confused with true iron deficiency anemia - this makes determining exact prevalence rates difficult 2, 4

• Gastrointestinal side effects (constipation, diarrhea, darkening of stool) are common with oral iron but generally self-limited 2

• Folic acid in doses above 0.1 mg daily may obscure pernicious anemia by improving hematologic parameters while neurologic manifestations progress 8

• In women of African, Mediterranean, or Southeast Asian ancestry, mild anemia unresponsive to iron therapy may be due to thalassemia minor or sickle cell trait 4

• Medications that decrease iron absorption include antacids, and risk factors for iron deficiency include vegetarian diet, gastrointestinal disease, and short interval between pregnancies 2

Postpartum Management

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

• Risk factors for postpartum anemia include anemia persisting through the third trimester, excessive blood loss at delivery, and multiple birth 1

• For mild postpartum iron-deficiency anemia, administer oral iron therapy 5

• For moderate-to-severe postpartum anemia (hemoglobin <95 g/L), administer intravenous iron therapy 5

• Continue iron supplementation throughout pregnancy and postpartum period to prevent recurrence 1

• Monitor breastfed infants for gastrointestinal toxicity (constipation, diarrhea) if mother is receiving intravenous iron 6