Iron Supplementation in Pregnancy
Recommended Dosage
All pregnant women should receive 30 mg of elemental iron daily starting at the first prenatal visit as universal prophylaxis, with the dose increased to 60-120 mg daily if anemia develops. 1
Universal Prophylaxis (All Pregnant Women)
- Start 30 mg/day of oral elemental iron at the first prenatal visit and continue throughout pregnancy 2, 1
- This low-dose regimen effectively prevents iron deficiency anemia while minimizing gastrointestinal side effects 2
- Once hemoglobin normalizes for gestational age, maintain the 30 mg/day dose 1
Treatment Dosing (For Diagnosed Anemia)
- For mild to moderate anemia, prescribe 60-120 mg/day of elemental iron 2, 1
- The 60 mg dose is supported by high-quality evidence showing it substantially reduces anemia incidence (from 47% to 16% in placebo-controlled trials) without significantly increasing side effects 3
- Doses above 60 mg increase side effects without proportional benefit—side effects occur in 32.4% at 60 mg, 40.3% at 120 mg, and 72% at 240 mg 4
Screening and Monitoring Algorithm
Initial Assessment
- Screen all pregnant women at the first prenatal visit using hemoglobin or hematocrit 1
- Repeat screening at 24-28 weeks gestation 1
- If screening is positive, confirm with repeat testing before escalating treatment 1
Response Monitoring
- Reassess hemoglobin or hematocrit after 4 weeks of treatment 1
- Expected response: increase of ≥1 g/dL in hemoglobin or ≥3% in hematocrit 1
- If no response after 4 weeks despite confirmed compliance, perform additional testing including mean corpuscular volume, red cell distribution width, and serum ferritin 1
Optimization Strategies
Absorption Enhancement
- Take iron on an empty stomach to maximize absorption 5
- Consider taking with vitamin C, though evidence is limited 5
- Avoid concurrent use with food, antacids, or proton pump inhibitors as they significantly decrease absorption 5
Managing Side Effects
- Gastrointestinal symptoms (nausea, constipation, vomiting) are common but generally self-limiting 5, 1
- Lower doses (30 mg) are as effective as higher doses (60-120 mg) for prophylaxis and cause fewer side effects 2
- Simplified once-daily dosing improves compliance 2
When to Escalate to Intravenous Iron
Consider IV iron therapy for: 1
- Severe anemia
- Intolerance to oral iron despite dose adjustment
- Lack of response to oral iron after 4 weeks with confirmed compliance
- Need for rapid correction of anemia
Ferric carboxymaltose is the preferred IV option due to rapid effectiveness and better tolerability 1
Special Populations
Vegetarian Women
- May require nearly double the iron supplementation due to lower absorption of non-heme iron from plant sources 5, 1
- The Institute of Medicine notes non-heme iron absorption is significantly lower than heme iron from meat 2
High-Risk Groups
- Women with ferritin ≤30 μg/L should receive 60-80 mg/day 6
- Women with ferritin <15 μg/L (depleted stores) require therapeutic doses of 100 mg/day 6
Important Clinical Outcomes
Maternal Benefits
Neonatal Benefits
- 19% reduction in low birthweight (<2500 g) infants 7
- Mean birthweight increase of 30.81 g 7
- Protection of infants from iron deficiency anemia 8
Critical Pitfalls to Avoid
- Do not assume compliance without verification—frequent side effects lead to treatment discontinuation 5
- Avoid high-dose prophylaxis (>60 mg) in non-anemic women—increases side effects without additional benefit 2, 8
- Do not delay treatment waiting for additional testing in non-acutely ill pregnant women with positive screening 1
- Monitor for excessive hemoglobin elevation—levels >15.0 g/dL or hematocrit >45.0% in second/third trimester may indicate poor blood volume expansion and pregnancy complications 1