What is a reasonable estimate of breast milk intake for a 2.3 kg, 35-week preterm infant?

Breast Milk Intake for a 2.3 kg, 35-Week Preterm Infant

For a 2.3 kg preterm infant at 35 weeks gestation, target approximately 345-460 mL of breast milk per 24 hours (150-200 mL/kg/day), divided into 8-12 feedings, to achieve the recommended weight gain of 17-20 g/kg/day (approximately 39-46 grams daily for this infant). 1

Feeding Volume Calculation

• Standard fluid intake for preterm infants is 150-200 mL/kg/day once full enteral feeds are established 2
• For a 2.3 kg infant, this translates to 345-460 mL per 24 hours 2
• Breast milk provides approximately 0.67 kcal/mL (2.8 kJ/g), so this volume delivers roughly 230-310 kcal/day (100-135 kcal/kg/day) 2

Feeding Frequency and Pattern

• Preterm infants require 8-12 feedings per 24 hours during the first months of life 1
• For a 2.3 kg infant, this means approximately 29-58 mL per feeding if divided into 8-12 feeds 1
• Feed every 2-3 hours to maintain adequate intake and prevent excessive weight loss 2

Growth Monitoring Requirements

• The target weight gain is 17-20 g/kg/day, which equals approximately 39-46 grams per day for this 2.3 kg infant 1, 3
• Weight gain below this target (such as 9 g/kg/day or ~21 grams/day) requires immediate intervention 1, 3
• Monitor weight, length, and head circumference serially to assess nutritional adequacy 2, 3

Fortification Considerations

• Breast milk fortification is often necessary for preterm infants to achieve intrauterine growth rates, as human milk composition varies considerably 4
• Energy intakes of 90-120 kcal/kg/day (approximately 207-276 kcal/day for this infant) are needed to approximate intrauterine growth rates 1
• For inadequate weight gain, increase caloric intake to approximately 120 kcal/kg/day (276 kcal/day for 2.3 kg) to promote catch-up growth 3
• Standard fortification with commercial human milk fortifier is the typical approach, though targeted fortification remains controversial due to feasibility concerns 5

Critical Pitfalls to Avoid

• Do not wait for prolonged periods if weight gain is inadequate—delayed intervention leads to impaired neurodevelopment 3
• Assess for oral-motor dysfunction early, as feeding coordination issues are common in preterm infants and require skilled evaluation 2
• Monitor for gastroesophageal reflux, which significantly affects feeding tolerance and weight gain in preterm infants 2, 3
• If weight loss exceeds 12% from birth or clinical dehydration is evident, supplement with formula or expressed breast milk and consider intravenous fluids if oral intake is questionable 2

Electrolyte and Mineral Requirements

• Ensure adequate sodium (4-7 mEq/kg/day) and potassium (2-4 mEq/kg/day) intake 2, 3
• Provide calcium (120-230 mg/kg/day), phosphorus (60-140 mg/kg/day), and magnesium (7.9-15 mg/kg/day) for enteral feeding 2, 3
• Iron supplementation of 2-3 mg/kg/day is recommended if receiving human milk or fortified human milk 2, 3

Follow-Up Schedule

• Schedule weight checks within 48-72 hours after initiating any feeding interventions 1
• For ongoing concerns, monitor weight every 2-4 weeks 1
• Adjust feeding volumes and fortification based on actual weight gain patterns rather than predetermined schedules 2