Nutritional Needs of the Preterm Infant

In general, the needs of the preterm infant following discharge from the neonatal intensive care unit NICU are as follows:
  1. Energy needs: 120-130 kcal/kg/day to grow 15-20 g/day as they catch up to term (potentially more for ELBW). These needs decrease as the infant nears 40 weeks gestational age, but the recommendations do not account for “catch up” growth for SGA preterm infants or infants with suboptimal weight gain in the NICU. [Martin: 2006] [Lapillonne: 2013]
  2. Protein needs: 2-3 g/kg/day – on the lower end closer to term, on the higher end when around 34 weeks GA. [Lapillonne: 2013]
  3. Calcium needs: 70-140 mg/kg/day – on the lower end closer to term, on the higher end when around 34 weeks GA [Lapillonne: 2013]
  4. Iron supplementation: 2-4 mg/kg/day – on the lower end for routine care of late preterm infants. Start around 4 weeks of life and continue until approximately 12 months of age, or when child can ingest adequate iron from food or formula. May require monitoring to adjust. [Lapillonne: 2013] There is lack of consensus on this however, and consideration must be given to use of iron-containing formulas, fortifiers, multivitamins with added iron, and foods as well as the history of erythrocyte transfusions, as premature infants may also develop iron overload. Common formulations for babies contain 15 mg of elemental iron per 1 mL of liquid. Iron supplementation can cause gastric upset and hard or darkened stools.
  5. Volume of feedings: typically 150-200 ml/kg/day for infants taking 20 kcal/kg/day, may be decreased for infants taking increased caloric density breast milk or formula or with certain medical conditions requiring volume restriction. [Lapillonne: 2013]
  6. Lipids: docosahexaenoic acid (DHA) and arachadonic acid (ARA) requirements are higher in preterm (including late preterm) infants. Once infants reach 40 weeks GA, they are considered the same as term infants.
  7. Vitamin D: Supplementation is recommended for all infants to help with bone development and other aspects of immune function and development. Typical daily dosing is 400 IU enterally. The Vitamin D3 formulation, cholecalciferol, tends to have more predictable enteral absorption than Vitamin D2, ergocalciferol. Even when a breastfeeding mother supplements her Vitamin D, the levels in breast milk do not meet the recommended daily requirements. Formula-fed babies need to drink at least 34 ounces (1 liter) of formula daily to obtain the recommended daily allowance of Vitamin D. Common formulations of Vitamin D3 for babies contain either 400 IU per 1 mL or 400 IU per drop. Side effects are uncommon; however, some infants find the supplement unpalatable. Please see Calcium and Vitamin D for further information about recommended intakes.
  8. Other: Heterogeneous recommendations. Selective monitoring of blood urea nitrogen, ferritin, retinol binding protein, alkaline phosphatase and Vitamin D 25-OH may be valuable in determining the nutritional status of high-risk infants.

Breast milk continues to be the best form of nutrition for the term infant when this is an option for the mother and child. On average, breast milk provides 20 kcal of energy per 1 ounce. To meet the increased nutritional needs of preterm infants, breast milk may be fortified with products such as Enfamil or Similac Human Milk Fortifier, although these may not be available for home use. Instead, infant formula powders can be added to expressed breast milk to increase the caloric density. If increased calories are needed, breastfeeding mothers can be encouraged to substitute a set number of the breastfeeding episodes with feeds given by cup, spoon, syringe or bottle, or supplement through a tube attached at the nipple during breastfeeds. [Phillips: 2013] In some facilities, breast milk composition can be analyzed in order to make tailored adjustments; however, this is not yet in widespread practice in the United States. If fortifiers are used, the clinician can calculate the added Vitamin D and iron to determine if additional supplementation is indicated.

The number of formulas approximating breast milk has increased over several decades. Specialized formulas are created for preterm infants to match the changing requirements as well as respond to the increase in knowledge of the needs of the preterm infant. At the time of discharge from the NICU, formula-fed preterm infants may continue to require added nutrition to catch up to term weight and address their specialized nutritional needs. Preterm formulas developed for after-hospital care include 22 kcal/30 ml formulations such as Similac Neosure Advance and Enfacare Lipil, and should be considered particularly for infants with birth weights <1500g for 9-12 months.

Premature infant formulas are specially mixed to preserve the bone integrity of the newborn, providing appropriate levels of vitamin D and calcium for the preterm infant. Without these, or if infants experience complications that interfere with adequate nutrition, osteopenia may result and fractures could occur. Fracture is an infrequent finding in premature infants and warrants further investigation.


Reviewing Author: Mary Ann Nelin, MD - 12/2014
Content Last Updated: 1/2015

Page Bibliography

Lapillonne A, O'Connor DL, Wang D, Rigo J.
Nutritional recommendations for the late-preterm infant and the preterm infant after hospital discharge.
J Pediatr. 2013;162(3 Suppl):S90-100. PubMed abstract

Martin RJ, Fanaroff AA, Walsh MC ed.
Fanaroff and Martin's neonatal‐perinatal medicine diseases of the fetus and infant, Vols I and II.
8th ed. Philadelphia, PA: Elsevier Mosby; 2006. 0-323-02966-3

Phillips RM, Goldstein M, Hougland K, Nandyal R, Pizzica A, Santa-Donato A, Staebler S, Stark AR, Treiger TM, Yost E.
Multidisciplinary guidelines for the care of late preterm infants.
J Perinatol. 2013;33 Suppl 2:S5-22. PubMed abstract / Full Text
Gives guidelines for caring for late preterm infants in the hospital and after discharge. Includes short- and long-term follow up; each care recommendation is associated with counseling points to share with the family.