Treatment of Iron Deficiency in Early Pregnancy
For a 32-year-old woman at 7 weeks gestation with a ferritin of 7 µg/L, prescribe 60-120 mg of elemental oral iron daily immediately and continue until hemoglobin normalizes for gestational age, then reduce to 30 mg/day for the remainder of pregnancy. 1
Immediate Treatment Approach
Start oral iron supplementation now without delay. A ferritin of 7 µg/L indicates depleted iron stores (threshold for deficiency is <30 µg/L in pregnancy), and at 7 weeks gestation, this patient needs aggressive repletion before iron demands increase exponentially in the second and third trimesters. 2
Specific Dosing Regimen
Prescribe 60-120 mg of elemental iron daily as the treatment dose for established iron deficiency 1, 3
Common formulations include:
Continue treatment dose until hemoglobin normalizes for gestational age, then reduce to 30 mg elemental iron daily for maintenance 1
Monitoring Protocol
Check hemoglobin and hematocrit after 4 weeks of treatment. You should see hemoglobin increase by at least 1 g/dL or hematocrit by 3%. 1, 3
- If anemia develops or fails to respond despite documented compliance, obtain additional testing including MCV, RDW, and repeat serum ferritin 1
- Continue monitoring hemoglobin at least once per trimester throughout pregnancy 7
- Screen again at 4-6 weeks postpartum, as this patient is at high risk for persistent anemia 1, 3
Optimizing Absorption and Compliance
Counsel the patient to take iron at bedtime to minimize gastrointestinal side effects (nausea, constipation, altered bowel movements are common). 8, 4
Dietary counseling is essential:
- Recommend iron-rich foods including meat, poultry, fortified cereals, and certain fruits/vegetables 1, 3
- Advise taking iron with vitamin C-rich foods to enhance absorption 1
- Separate calcium supplements and antacids by at least 2 hours from iron doses, as they significantly impair absorption 8
- Do not take within 2 hours of tetracycline antibiotics 4
Warn the patient about expected side effects:
- Darkening of stool and urine is normal 8
- Possible teeth/gum staining (can be minimized by taking tablets whole rather than chewing) 8
When to Consider Intravenous Iron
While oral iron is first-line treatment, consider IV iron if:
- The patient cannot tolerate oral iron despite trying different formulations 2
- There is no response to oral iron after 4 weeks with documented compliance 1, 2
- Severe anemia develops (Hb <9.0 g/dL) 1
- Clinical need for rapid correction arises as pregnancy advances 2
Intravenous iron sucrose and ferric carboxymaltose are the best-studied options in pregnancy and show superior efficacy compared to oral iron, with mean hemoglobin improvements of 7.17 g/L and 8.52 g/L respectively versus oral ferrous sulfate. 9 However, these should be reserved for the specific indications above, not as first-line therapy.
Critical Timing Consideration
Early treatment at 7 weeks is crucial. Iron deficiency in the first trimester, if left untreated, leads to inadequate iron stores for the massive expansion of maternal erythrocyte mass and fetal/placental development in the second and third trimesters. 2, 10 Women who enter pregnancy with depleted stores (like this patient) cannot meet increased demands through diet alone and will develop frank anemia without supplementation. 11
Common Pitfall to Avoid
Do not wait for anemia to develop before treating. This patient has iron deficiency (ferritin 7 µg/L) even if her hemoglobin is currently normal. Treating now prevents progression to iron deficiency anemia and its associated complications including preterm delivery, low birthweight, and maternal fatigue. 2, 10