Nutrition for VLBW Infants and Newborns

Feeding and Nutritional Concerns

Many preterm infants may have feeding issues after discharge from the nursery or NICU. Monitoring for feeding issues and implementing early optimized nutrition can reduce the postnatal growth delays often seen in preterm newborns and infants. 

Preterm Birth Numbers

In the United States, 10.4% of the approximately 3.62 million neonates born in 2024 were born preterm (<37 completed weeks of gestation).

• 2.72% (~98,000) were early preterm births (<34 completed weeks of gestation).
• 7.69% (~278,000) were late preterm births (34–36 completed weeks of gestation). 
  • The late preterm birth rate has increased since 2021 and is at its highest rate since 2007.

Care of the Preterm Newborn and Infant After Discharge 

Preterm newborns and infants being discharged home need to be monitored closely for 

• Adequate feeding patterns and weight gain
• Breastfeeding success
  • Assess and provide maternal lactation support to promote breastfeeding after discharge.
• Iron, vitamin, and mineral status
  • Calcium and phosphorus: Assess very low birth weight (VLBW) infants for rickets and adequacy of intakes beginning 4 to 5 weeks after birth.
    • Calcium intake of 150 to 220 mg/kg/d for preterm infants who are fully enterally fed.
    • Phosphorus intake of 75 to 140 mg/kg/d. 
    • 10% to 20% of hospitalized infants with birth weight <1,000 g have radiologically defined rickets (metaphyseal changes), and fractures develop in some. 
  • Iron: After 2 weeks of age, provide up to 2 to 3 mg/kg/d of total enteral iron.
    • Iron supplements should be continued until 6 to 12 months of age, depending on diet.
    • Monitor VLBW infants with regular measurements of ferritin to assess iron status. 
    • If ferritin level is <35 mcg/L, the iron dose should be increased.
  • Vitamin D: For infants who weigh <1,500 g, 400 IU/kg/d of vitamin D is sufficient, although 200 IU per day is acceptable.
    • Increase to 400 IU/day when the weight exceeds 1,500 g and the infant is tolerating full enteral nutrition.

Preterm newborns and infants have increased energy needs compared to the term neonate and infant, requiring calorically dense enteral nutrition.  

• Unfortified human milk and standard infant formula are not sufficient for optimal growth of preterm infants. 
• Preterm infants fed standard infant formulas gain a higher percentage of their weight as fat when compared with a fetus of the same maturity. 
• Infants born <1,000 g and discharged before a weight of 2,000 g require fortification of both human milk and infant formula. 
• Consider fortifying human milk or use fortified infant formula for a minimum of 12 weeks after discharge.  

Fortification options for preterm infants who are receiving human milk

• Several bottle-feedings per day of post-discharge formula
• Powdered post-discharge formula (22–24 kcal/oz) (less preferred because it cannot be sterilized) 

Vitamin supplements for infants fed human milk include 

• Supplements of vitamins A, D, and E are readily available as oral solutions (none contain vitamin K).
• The bovine-based human milk fortifiers supply added vitamin D when used after discharge. 
  • No need to supplement preterm infants without cholestasis with more than 400 IU per day of vitamin D after hospital discharge.
• Preterm infants fed human milk after discharge will likely need iron supplements until appropriate iron-containing complementary foods are introduced. 

Vitamin supplements for formula-fed infants

• Fat-soluble vitamins
  • If preterm infants are discharged on standard term infant formulas, they may not consume enough volume of the formula to meet the recommended amounts of vitamins until they reach a weight of 3 kg. 
    • It is likely not necessary to supplement with fat-soluble vitamins for infants >3 kg, except for vitamin D. 
  • Infants discharged on formulas designed for preterm infants likely supply adequate amounts of fat-soluble vitamins. 

Feeding Difficulties 

The sucking and rooting reflexes are not fully developed until 36 to 38 weeks’ gestation, so feeding difficulties may be present in early term neonates as well as preterm neonates. 

The most common feeding problems, which can result in rehospitalization, are  

• Oral-motor dysfunction
• Avoidant feeding behaviors
• Decreased intake resulting from feeding fatigue 

Parents should be made aware of feeding red flags of preterm neonates. 

• Feeding duration longer than 25 to 30 minutes or fewer than 6 feedings per day
• Fussiness, distress, or difficulty breathing during feedings
• Difficulty waking the newborn for feeding or difficulty completing a full feeding (eg, falls asleep repeatedly)
• Newborn refusal of feedings or gagging, coughing, cyanosis, or frequent choking while feeding 

Other Specific Nutritional Considerations for Preterm Newborns and Infants  

Human milk is the preferred feeding at discharge with several supplemental feeds of preterm formula for VLBW infants. 

• Less than half (42%) of all VLBW infants are receiving any human milk by the time of discharge.
• Exclusively human milk-fed preterm infants are at higher risk of nutritional deficiencies due to high variability in the nutrient content of human milk and the gradual decline in protein content over time.
• When human milk is not available, a nutrient-enriched formula for preterm infants may be used.
  • Soy-based formulas are not recommended for preterm infants.  
  • Current evidence does not support the routine, universal administration of probiotics to preterm infants, particularly those with a birth weight <1,000 g.

Specific nutrient recommendations for VLBW preterm infants are contained in a series of consensus reports, the most recent of which was updated in 2023. (ref) (ref) (ref)  

Notable nutrient recommendations include 

Vitamin A 

• Low vitamin A reserves and impaired absorption place the preterm infant at risk of developing vitamin A deficiency. 
• Sufficient vitamin A status reduces the incidence and severity of lung disease in the preterm infant.
• Special formulas for preterm infants supply an adequate amount (3,045 mcg/L, 375 mcg/100 kcal).
• Human milk fortifiers, when used as directed, will provide an additional 1,860 to 2,850 mcg/L. 

Zinc 

• The zinc concentration of colostrum is high (5.4 mg/L), but its concentration in human milk rapidly declines to concentrations of 2.5 mg/L by 1 month and 1.1 mg/L by 3 months postpartum.
• These concentrations of zinc are inadequate to meet the requirements of the preterm infant. 
• Estimated enteral recommendations for zinc are 2 to 3 mg/kg/d.
• The zinc in human milk fortifiers and preterm formulas provide sufficient zinc.  

Water-soluble vitamins 

• The recommended enteral intakes of water-soluble vitamins for preterm infants fed human milk may be achieved by using a vitamin-containing human milk fortifier, as relatively few of these vitamins are provided by standard, oral multivitamin supplements. 
• In formula-fed preterm infants, recommendations may be met by feeding formulas designed for preterm infants.
• There are no guidelines for supplementing preterm infants with water-soluble vitamins after hospital discharge, and no published studies are available. 

Folate 

• Preterm infants are at increased risk of folate deficiency because of limited hepatic stores and rapid postnatal growth.
• Folate status, assessed by red blood cell folate concentrations, improves among those provided supplemental folic acid.

Vitamin E 

Pharmacologic doses of vitamin E for the prevention or treatment of retinopathy of prematurity, bronchopulmonary dysplasia, and intraventricular hemorrhage are not recommended.

Human Milk and Donor Milk for Preterm Infants

Human milk from the infant’s own mother is the ideal enteral feeding for the preterm infant.  

• Human milk contains living cells including stem cells and bioactive factors that aid health and development.
• Human milk is well tolerated and promotes earlier achievement of full enteral feeding compared with infant formula.
• All nutrients are present in inadequate concentrations to meet the nutritional needs of the preterm infant.
  • Shortfalls are particularly high for protein, calcium, phosphorus, and zinc. 

The energy density of preterm and term human milk is approximately 65 to 67 kcal/dL or about 20 kcal/oz at 21 days of lactation.  

• Energy density in human milk varies largely between mothers and is affected by time of day of lactation and fraction of milk pumped.
• Many preterm infants <1,500 g birth weight receive a diet of mother’s own milk supplemented with pasteurized donor human milk. 
• Donor human milk is generally lower in protein than preterm milk because it is term milk donated from mothers of older infants. 
• Infants fed donor milk may have slower growth and require additional calories.
• Fortification of human milk to 24 kcal/oz is required and sufficient for most infants. 

The use of donor milk versus commercially available infant formulas significantly reduces the risk of necrotizing enterocolitis. (ref)(ref)(ref) 

• Donor milk should be used when mother’s milk is unavailable or contraindicated for newborns with VLBW.
• Donor milk requires fortification in VLBW infants.