What is the management and treatment of anemia in pregnancy?

Anemia in Pregnancy: Comprehensive Management

Definition and Diagnostic Thresholds

Anemia in pregnancy is defined as hemoglobin <11 g/dL in all trimesters, affecting 32 million pregnant women globally and contributing to over 115,000 maternal deaths annually. 1, 2

• Use hemoglobin <11 g/dL or hematocrit <33% as diagnostic cutoffs for all trimesters, not the traditional trimester-specific values 1, 2
• Severe anemia is defined as hemoglobin <7 g/dL, moderate as 7-9.9 g/dL, and mild as 10-10.9 g/dL 1
• Fetal anemia is diagnosed when hemoglobin is >2 SD below the mean for gestational age, with severe fetal anemia defined as <0.55 multiples of the median 3

Screening Protocol

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

• Confirm positive screening with repeat testing before initiating treatment 1
• In non-acutely ill pregnant women, make a presumptive diagnosis of iron deficiency anemia and begin treatment immediately without waiting for additional testing 1, 4
• Screen postpartum at 4-6 weeks if risk factors present: anemia persisting through third trimester, blood loss >300 mL at delivery, or multiple birth 1, 5

Prevention Strategy

All pregnant women should receive 30 mg/day of elemental iron starting at the first prenatal visit, regardless of anemia status. 1

• This universal supplementation prevents iron deficiency anemia development during pregnancy 1
• Add folic acid supplementation as part of routine prenatal care to prevent neural tube defects 2, 6
• In malaria-endemic areas, provide malaria chemoprophylaxis and anti-helminthic treatment 2

Treatment Algorithm for Maternal Anemia

Mild to Moderate Anemia (Hb 7-10.9 g/dL)

Prescribe 60-120 mg/day of elemental iron orally as first-line treatment. 1, 4

• Provide dietary counseling on iron-rich foods (meat, poultry, fortified cereals) and factors enhancing absorption 1, 4
• Warn patients about expected gastrointestinal side effects: dark stool, constipation, and abdominal discomfort, which are generally self-limited 1, 5
• Vegetarian women require nearly double the supplementation (up to 240 mg daily) due to lower absorption of non-heme iron 1, 5

Monitoring Response

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, 5
• If no response after 4 weeks despite compliance and absence of acute illness, perform additional testing: mean corpuscular volume, red cell distribution width, and serum ferritin 1, 5
• Once hemoglobin normalizes for gestational age, reduce iron dose to 30 mg/day for maintenance 1

Severe Anemia or Treatment Failure

Consider intravenous iron therapy for severe anemia (Hb <7 g/dL), intolerance to oral iron, or lack of response to oral iron after 4 weeks despite compliance. 1, 7

• Before switching to IV iron, confirm compliance with oral regimen and rule out other causes of iron-refractory anemia 1, 4
• Ferric carboxymaltose is the preferred intravenous iron option due to rapid effectiveness and better tolerability 1, 5, 7
• IV iron is particularly indicated in advanced pregnancy when rapid iron repletion is needed 7
• Close surveillance during administration is recommended for all IV iron products, though anaphylactic reactions are extremely rare with non-dextran products 7

Fetal Anemia Management

Pregnancies with a fetus at significant risk for anemia should be delivered at 37-38 weeks gestation unless indications develop earlier. 3

• Most common causes in the United States are maternal alloimmunization and parvovirus infection 3
• Monitor middle cerebral artery peak systolic velocity by Doppler to detect fetal anemia non-invasively 3
• Severe fetal anemia (hemoglobin <5 g/dL) can lead to hydrops fetalis and fetal death 3
• Fetal intravascular transfusion may be needed for severe cases, particularly with parvovirus-induced aplastic crisis 3

Postpartum Management

Continue iron supplementation throughout pregnancy and the postpartum period to prevent recurrence. 1, 4

• Screen at 4-6 weeks postpartum using hemoglobin or hematocrit in at-risk women 1, 5
• Use hemoglobin <12 g/dL or hematocrit <36% as diagnostic thresholds for postpartum anemia 5
• For postpartum anemia, prescribe 60-120 mg elemental iron daily orally for mild cases 5
• Switch to IV iron for moderate-to-severe postpartum anemia (Hb <9.5 g/dL) or when rapid repletion is needed 5, 7

Critical Pitfalls to Avoid

Do not stop iron supplementation at delivery if risk factors for postpartum anemia are present. 5

• Hemoglobin >15 g/dL or hematocrit >45% in second or third trimester warrants evaluation for poor blood volume expansion and potential pregnancy complications 1
• Do not assume oral iron failure without confirming medication compliance and ruling out concurrent inflammatory conditions 5
• Refer to hematology if hemoglobin <9 g/dL or hematocrit <27% for further evaluation 5
• Consider gastroenterology consultation if occult bleeding or malabsorption is suspected 5

Relationship to Postpartum Hemorrhage

Anemia in pregnancy significantly increases the risk and impact of postpartum hemorrhage, making prevention and treatment critical for maternal safety. 2

• Anemic women have reduced physiologic reserve to tolerate blood loss at delivery 2
• Optimal anemia management reduces both the incidence and severity of PPH complications 2