What is the recommended daily elemental iron intake for a healthy pregnant adult with a singleton pregnancy and no iron‑overload disorders?

Iron Requirements in Pregnancy

Pregnant women require 27 mg of elemental iron daily according to the Institute of Medicine, and routine prophylaxis should begin with 30 mg elemental iron daily at the first prenatal visit, delivered through standard prenatal vitamins. 1

Baseline Requirements for All Pregnant Women

• The Recommended Dietary Allowance is 27 mg elemental iron per day for all pregnant women, regardless of trimester. 2, 1
• Standard prenatal vitamins typically contain 30 mg elemental iron, which aligns closely with the Institute of Medicine recommendation and serves as the foundation for routine prophylaxis. 1
• This 30 mg daily dose should be initiated at the first prenatal visit and continued throughout gestation. 1
• Most pregnant women (77%) already use multivitamin supplements containing approximately 48 mg of iron, suggesting widespread adherence to supplementation practices. 2

Higher-Dose Supplementation for High-Risk Populations

Women at increased risk for iron deficiency require 60-100 mg elemental iron daily rather than the standard 30 mg dose. 2, 1

High-risk groups include:

• Non-Hispanic Black women 1
• Mexican-American women 1
• Women with short inter-pregnancy intervals 1
• Women with parity ≥ 2 1
• Women following vegetarian diets, who may require up to 54 mg daily because non-heme iron from plant sources is absorbed less efficiently than heme iron from animal sources. 2, 1

Treatment of Diagnosed Iron-Deficiency Anemia

Therapeutic dosing of 60-120 mg elemental iron daily is the standard of care for pregnant women with confirmed iron-deficiency anemia. 2, 1, 3

The treatment algorithm is:

• Start 60-120 mg elemental iron daily immediately upon diagnosis. 1, 3
• Continue therapeutic dose for 4 weeks, then reassess hemoglobin concentration. 1
• Expect hemoglobin to rise by ≥1 g/dL (or hematocrit increase of ≥3%) after 4 weeks of adherent therapy. 1
• Once hemoglobin normalizes for gestational age, reduce to 30 mg elemental iron daily for maintenance throughout the remainder of pregnancy. 1

Optimizing Absorption and Minimizing Side Effects

Separate iron supplements from calcium-containing products and antacids by several hours, as co-administration markedly reduces iron absorption. 1, 3

Additional strategies include:

• Consider taking iron at bedtime to reduce gastrointestinal side effects. 3
• Counsel patients about iron-rich foods and vitamin C intake, which enhances absorption. 3
• Be aware that side effects (nausea, constipation, darkening of stool) increase with higher doses but are generally not significantly different between 60 mg and placebo groups. 4

Postpartum Management

Discontinue iron supplementation at delivery for women without ongoing risk factors; routine postpartum continuation is not recommended. 1

• Screen for anemia at 4-6 weeks postpartum only if risk factors are present: persistent third-trimester anemia, significant peripartum blood loss, or multiple gestation. 1
• If postpartum anemia is identified in breastfeeding women, prescribe 60-120 mg elemental iron daily and recheck hemoglobin after 4 weeks. 5

Common Pitfalls to Avoid

Failure to identify and appropriately dose high-risk women is a critical error. 1

• Do not use the standard 27-30 mg dose for high-risk populations who require 60-100 mg daily. 1
• Do not continue routine supplementation postpartum in women without risk factors. 1, 5
• If hemoglobin fails to increase by ≥1 g/dL after 4 weeks of compliant oral therapy, evaluate for alternative etiologies such as thalassemia minor or sickle-cell trait, especially in women of African, Mediterranean, or Southeast Asian ancestry. 1, 6
• Laboratory assessment should include mean corpuscular volume, red-cell distribution width, and serum ferritin to differentiate true iron deficiency from other causes. 1