What is the treatment for iron deficiency (low iron) in pregnant women?

Treatment of Iron Deficiency in Pregnancy

For pregnant women with confirmed iron deficiency anemia, prescribe 60-120 mg of elemental iron daily via oral supplementation, which should be started immediately upon diagnosis. 1, 2

Primary Prevention (All Pregnant Women)

• Start low-dose oral iron supplementation (30 mg/day) at the first prenatal visit for all pregnant women 1
• Prenatal vitamins typically contain 30-48 mg of elemental iron, which meets this prophylactic requirement 3
• Encourage consumption of iron-rich foods and foods that enhance iron absorption (such as vitamin C-containing foods) 1, 2

Treatment of Confirmed Iron Deficiency Anemia

Initial Oral Iron Therapy

• Prescribe 60-120 mg of elemental iron daily (typically ferrous sulfate 325 mg daily) as first-line treatment 1, 2
• Begin treatment immediately without waiting for additional confirmatory testing if the pregnant woman is not acutely ill 2
• Continue treatment throughout pregnancy and into the postpartum period 2

Optimizing Oral Iron Absorption

• Take iron supplements at bedtime to reduce gastrointestinal side effects 3, 2
• Avoid taking calcium supplements and antacids concurrently, as they decrease iron absorption; separate by several hours 3, 2
• Counsel patients about dietary factors that enhance absorption, particularly vitamin C 2

Monitoring Response to Treatment

• Recheck hemoglobin or hematocrit after 4 weeks of treatment 1, 2
• Expected response: hemoglobin should increase by ≥1 g/dL or hematocrit by ≥3% 1
• Once hemoglobin normalizes for gestational age, decrease iron dose to 30 mg/day 1

When Oral Iron Fails

Criteria for Treatment Failure

If after 4 weeks the anemia does not respond to oral iron therapy (no increase in hemoglobin by 1 g/dL) despite confirmed compliance and absence of acute illness, further evaluation is required 1, 2

Additional Testing for Non-Responders

• Obtain MCV, RDW, and serum ferritin concentration 1
• In women of African, Mediterranean, or Southeast Asian ancestry, consider thalassemia minor or sickle cell trait as alternative diagnoses 1, 2

Intravenous Iron Therapy

• Consider IV iron for: oral iron intolerance, malabsorption, treatment failure despite compliance, or clinical need for rapid correction in advanced pregnancy 2, 4, 5
• Ferric carboxymaltose is the preferred IV formulation during pregnancy due to rapid effectiveness and better tolerability 2, 5
• IV iron administration requires settings with resuscitation facilities available due to rare but serious allergic reactions 2, 5

Severe Anemia Requiring Referral

• If hemoglobin is <9.0 g/dL or hematocrit is <27.0%, refer to a physician familiar with anemia management in pregnancy for further evaluation 1

Special Population Considerations

Higher-Risk Groups Requiring Closer Monitoring

• Vegetarian women may require almost twice as much iron due to lower absorption of non-heme iron from plant sources 3, 2
• Non-Hispanic Black and Mexican American women have higher prevalence of iron deficiency 3, 2
• Women with short intervals between pregnancies 3, 2
• Women with gastrointestinal conditions affecting absorption 2

Higher-Dose Prophylaxis for At-Risk Women

For women at higher risk of developing iron deficiency anemia, consider 60-100 mg elemental iron daily from early pregnancy rather than waiting for anemia to develop 3, 2

Postpartum Management

• Screen for anemia at 4-6 weeks postpartum only if risk factors are present (anemia continued through third trimester, excessive blood loss at delivery, or multiple birth) 1, 2
• If no risk factors exist, discontinue iron supplementation at delivery 1, 6
• For postpartum iron deficiency anemia, treat with 60-120 mg elemental iron daily and continue for 2-3 months after hemoglobin normalizes 1, 6

Common Pitfalls to Avoid

• Do not take iron within 2 hours of tetracycline antibiotics, as iron interferes with tetracycline absorption 7
• Failing to separate calcium supplements and antacids from iron doses, which significantly reduces iron absorption 3, 2
• Not identifying higher-risk women who need increased supplementation from early pregnancy 3
• Discontinuing treatment too early before iron stores are replenished 2, 6

Expected Side Effects (Counsel Patients)

Common gastrointestinal effects include nausea, constipation, or diarrhea 1, 7

• Darkening of stool or urine is expected and harmless 3, 7
• Possible staining of teeth and gums 1, 3