When should a healthy, exclusively breastfed infant be started on Enfamil Poly‑Vi‑Sol (iron) supplementation?

When to Start Poly-Vi-Sol with Iron in Healthy, Exclusively Breastfed Infants

Start iron supplementation at 4 months of age at a dose of 1 mg/kg/day for healthy, full-term, exclusively breastfed infants. 1, 2

Algorithmic Approach to Iron Supplementation Timing

For Healthy, Full-Term, Exclusively Breastfed Infants

Begin at 4 months:

• The American Academy of Pediatrics recommends initiating iron drops (approximately 1 mg/kg/day) at 4 months of age for exclusively breastfed term infants. 1, 2
• This timing reflects that term infants are born with adequate iron stores lasting approximately 4–6 months, after which external iron becomes necessary. 3, 1
• The recommendation carries moderate strength; evidence shows routine supplementation before 4 months offers no additional benefit in populations with low anemia prevalence. 1

Alternative approach at 6 months:

• If you prefer to wait, the CDC and WHO guidelines support starting iron supplementation at 6 months when complementary foods are introduced, provided the infant receives iron-fortified cereals (≥2 servings daily) or pureed meats. 3, 2
• However, do not delay beyond 6 months in exclusively breastfed infants without adequate iron-rich complementary foods, as 15–25% may develop iron deficiency by 9–12 months. 3

For High-Risk Infants Requiring Earlier Supplementation

Start between 2–6 weeks of age for:

• Preterm infants born <32 weeks: 2–3 mg/kg/day 4, 1, 2
• Low birth weight <2000 g: 2–3 mg/kg/day 4, 1, 2
• Marginally low birth weight 2000–2500 g: 1–2 mg/kg/day 4, 1, 2
• Small for gestational age infants needing catch-up growth 4, 2
• Continue supplementation until at least 12 months of age. 3, 2

For Infants in High-Risk Populations

Consider starting at 4–6 months if:

• Low socioeconomic status 4, 1
• Living in areas with high anemia prevalence 4, 1
• WIC-eligible, migrant, or refugee families 3

Rationale for the 4-Month Recommendation

The divergence between American (4 months) and WHO/European (6 months) guidelines reflects different risk-benefit assessments:

• Breast milk iron content is extremely low (approximately 0.35 mg/L) compared to iron-fortified formula (4–12 mg/L), though bioavailability is higher (~50% vs ~10%). 4, 2
• Maternal iron supplementation does not increase breast milk iron content, even with large daily doses, and cannot prevent infant iron deficiency. 3, 5
• Research shows that while most exclusively breastfed infants maintain adequate iron status through 6 months, 6–12% develop laboratory evidence of iron deficiency (though not necessarily anemia) by 6–9 months. 5, 6

Common Pitfalls to Avoid

• Do not use low-iron or non-fortified formulas if supplementing with formula; they pose unacceptable risk for iron deficiency. 7
• Do not give cow's, goat's, or soy milk before 12 months; these contain minimal bioavailable iron and increase iron deficiency risk. 3
• Do not assume dietary sources alone are sufficient after 6 months without verifying adequate intake of iron-fortified cereals or meats. 3, 8
• Do not delay screening in high-risk infants; screen at 9–12 months, repeat 6 months later, then annually from ages 2–5 years. 3

Practical Implementation at 4–6 Months

When starting supplementation:

• Administer iron drops (1 mg/kg/day) preferably between meals to improve absorption, though this may increase gastrointestinal side effects. 2
• Introduce iron-fortified infant cereal at 6 months (≥2 servings daily can meet requirements). 3, 2
• Provide vitamin C-rich foods with meals to enhance non-heme iron absorption. 3, 2
• Offer pureed meats when developmentally ready (after 6 months) to supply highly bioavailable heme iron. 3, 8