At what age should formula be weaned from a premature infant?

When to Wean Formula from Premature Infants

Formula should not be "weaned" in the traditional sense until 12 months corrected age, at which point transition to whole cow's milk is appropriate for most premature infants, following the same guidelines as term infants. 1, 2

Understanding the Question: Formula Duration, Not Solid Food Introduction

The term "weaning" requires clarification in the context of premature infants, as it encompasses two distinct processes:

• Introduction of complementary solid foods (which begins around 3-4 months corrected age)
• Discontinuation of formula as the primary milk source (which occurs at 12 months corrected age)

These are separate nutritional transitions that should not be confused. 3, 4

Formula as Primary Nutrition: Birth Through 12 Months Corrected Age

Standard Duration

• Continue iron-fortified infant formula as the primary milk source until 12 months corrected age (not chronological age). 1, 4
• Formula provides 24-32 ounces daily during months 6-12, with volume naturally decreasing as solid food intake increases but never falling below 24 ounces. 5
• Premature infants require specialized formulas (preterm or preterm follow-up formulas) that provide higher protein, calcium, phosphorus, vitamins, and minerals compared to standard term formulas. 1, 6

Special Considerations for Growth-Restricted Infants

• Infants discharged with subnormal weight for postconceptional age should receive postdischarge formula (not standard term formula) until at least 40 weeks postconceptional age, and possibly until 52 weeks postconceptional age. 4
• These specialized postdischarge formulas contain higher protein, minerals, trace elements, and long-chain polyunsaturated fatty acids. 4

Caloric Density Requirements

• Premature infants often require 24 kcal/oz formula initially, transitioning to 30 kcal/oz or higher as they approach 1 year of age, particularly those with chronic lung disease or poor growth. 1
• Standard 20 kcal/oz formula used for term infants is frequently insufficient for premature infants' catch-up growth needs. 1

Introduction of Complementary Foods (Solid Foods)

Timing Based on Corrected Age

• Begin introducing solid foods at 3-4 months corrected age (13-17 weeks corrected), not chronological age. 3, 7
• This timing balances developmental readiness (disappearance of extrusion reflex) with nutritional needs. 1, 3

First Foods

• Start with iron-fortified infant cereal as the first solid food, offering 2 or more servings daily to meet iron requirements. 1
• Introduce vitamin C-rich foods (fruits, vegetables, juice) by 6 months corrected age to enhance iron absorption, preferably with meals. 1
• Progress to pureed meats after 6 months corrected age when developmentally appropriate. 1

Critical Principle During Solid Food Introduction

• Solid foods complement but do not replace formula as the primary nutrition source until 12 months corrected age. 5, 7
• Formula volume may decrease from 32 ounces to 24 ounces daily as solids increase, but should not fall below this threshold. 5

Transition at 12 Months Corrected Age

Milk Type After 12 Months

• At 12 months corrected age, transition from formula to whole cow's milk (or continued breastfeeding if available). 2, 8
• Limit cow's milk intake to no more than 16-24 ounces (500-720 mL) daily to prevent displacement of other nutrient-dense foods and iron deficiency. 1, 2
• Whole milk is appropriate until age 2 years for most children; reduced-fat milk may be considered for those with family history of obesity or cardiovascular disease. 2

Why Not Earlier Than 12 Months

• Cow's milk, goat's milk, and soy milk are nutritionally inadequate before 12 months, lacking sufficient iron, vitamin D, and appropriate protein composition. 1, 8
• Early introduction of cow's milk increases risk of iron deficiency anemia. 1

Common Pitfalls to Avoid

Never Dilute Formula

• Formula must always be prepared at standard concentration (20 kcal/oz minimum) according to manufacturer instructions—never dilute below this concentration. 9
• Diluted formula causes hyponatremia, seizures, failure to thrive, and severe nutritional deficiencies. 9

Avoid Premature Discontinuation

• Do not transition to cow's milk before 12 months corrected age, even if the infant is eating substantial solid foods. 1, 8
• Premature transition results in inadequate iron, vitamin D, and protein intake. 1, 8

Monitor Growth Continuously

• Track weight, length, and head circumference at every visit to identify infants requiring continued specialized nutrition support beyond typical timelines. 4
• Poor growth indicates need for higher-calorie formula or extended use of postdischarge formulas. 1, 4

Excessive Milk After 12 Months

• After transitioning to cow's milk at 12 months, limit intake to 16-24 ounces daily to prevent iron deficiency and displacement of complementary foods. 1, 2

Monitoring and Supplementation

Iron Supplementation

• Premature infants who were low birthweight should receive 2-4 mg/kg/day iron drops starting at 1 month of age, continuing until 12 months. 1
• This is in addition to iron-fortified formula. 1

Vitamin D Supplementation

• All infants consuming less than 28 ounces of formula daily should receive 400 IU/day vitamin D supplementation. 2
• This recommendation continues after transition to cow's milk at 12 months. 2