Formula choices and composition

(Version 1.0 01/21/02 - 10/16/02)

The ideal food for the term neonate is breast milk. Although not fully nutritionally adequate for the extremely premature infant, preterm breast milk offers advantages over any synthetic formula and should be fed to premature infants whenever possible. Premature infants who have reached full feeds on breast milk should receive a human-milk fortifier to increase their caloric, protein, and mineral intake.

All postpartum mothers whose infants are in the NICU should be asked about providing breast milk for their infants. Although it is important not to add undue stress to new mothers with sick babies, mothers of VLBW infants should be made aware of the advantages of breast milk. Even if they were not planning on breastfeeding, many mothers are willing to pump breast milk for their sick premies; and they should be encouraged to do so.

If mothers are unable to provide breast milk for their infants, the following should serve as a guide for choosing an infant formula:

Standard cow’s milk-based term formulas include Similac with iron and Enfamil with iron. These formulas are 20 kcal/oz and should be fed to term infants without any contraindications.

Enfamil Premature Formula (EPF) and Similac Special Care (SSC) are both 24 kcal/oz formulas designed to nourish infants < 1800g birthweight. These formulas provide an increased caloric density, more protein, and more calcium and phosphorus to meet a growing premature baby’s needs. The quality of the nutrients in these formulas differs from term formulas as well. Preterm formulas include glucose polymers or corn syrup as the source of carbohydrate for premies who have developmental lactase deficiency, and use MCT oil as a fat source since premies have immature digestive processes for long-chain triglycerides.

Feed EPF or SSC to premature infants < 1800g and < 34 weeks postconceptual age.

Transitional formulas

Enfacare 22 and Similac NeoSure are 22 kcal/oz transitional formulas designed for the premature infant > 32 - 34 weeks PCA or the SGA/LBW term infant. Growing former micropremies continue to need additional calories, protein, and calcium for optimal nutrition for several months after their NICU discharge. However, long term feeding of premature formulas can lead to the ingestion of excessive vitamins and minerals. Therefore, the transitional formulas are designed as post-discharge nutrition to provide these infants with appropriately increased amounts of calories, protein, and calcium for the first 6 to 12 months of life outside the NICU.

Start some preterm infants (>32 - 34 weeks EGA and >1800g ) on a transitional formula. Change former micropremies who have reached > 1800 - 2000g to a transitional formula in preparation for discharge home.

The elemental formulas include: Pregestimil, Alimentum, Nutramigen, and Neocate. The carbohydrate, protein, and fat components of these formulas are broken down into simplified forms to ease digestion and absorption. Elemental formulas are often used in post-GI surgical patients to initiate feeds. They are also used in patients with formula intolerances, particularly cow’s milk protein intolerance, and in patients with malaborption.

Pregestimil, Alimentum, and Nutramigen all contain a casein hydrolysate as the protein constituent. These formulas also use glucose polymers, sucrose, starch, and/or corn syrup as the carbohydrate source rather than lactose.

Neocate contains an even more elemental protein source in the form of L-amino acids for the rare infant who is unable to tolerate the small peptides in casein hydrolysate. Neocate’s nitrogen supply includes free glutamine, which is the preferred fuel of proliferating enterocytes and has been shown to improve mucosal integrity in adult and animal models.

Portagen is a formula whose fat source consists mostly (85%) of medium-chain triglycerides which can be absorbed directly in the small intestine and causes minimal burden to the lacteals, lymphatics, and thoracic duct. This formula is chiefly used in patients with lymphatic leakage, for ex. chylothorax.

Whereas these formulas provide adequate nutrition for term infants, they provide inadequate amounts of calcium to nourish premature infants long term.

Prosobee and Isomil are formulas designed for term infants that use soy protein rather than cow’s milk protein. They also replace the carbohydrate lactose with sucrose and corn syrup solids. These formulas may be tried in patients with a family history or symptoms of cow’s milk protein intolerance, but 40% of babies with true cow’s milk sensitivity will also be sensitive to soy and should be placed on an elemental formula. Soy formulas may be used in patients with galactosemia or with transient lactase insufficiency (often secondary to gastroenteritis.)   These formulas do not provide adequate calories or protein for premature infants.  They also contain phytates which decrease calcium and phosphorus absorption; and they do not contain carnitine.

Highly specialized formulas are available for infants with inborn errors of metabolism who require unusual amino acid intakes. These formulas will be recommended by the Pediatric Genetic/Metabolic specialist. The Pediatric Metabolic nutritionist can help obtain these formulas.

Similac PM 60/40 is also a specialized formula used almost exclusively in infants with renal failure to minimize their renal phosphate load. It may also be used in rare infants with pathologic late neonatal hypocalcemia.

Pedialyte is an electrolyte-containing dextrose solution originally designed as oral rehydration therapy for infants and children with diarrhea and dehydration. Pedialyte may be used in the nursery as an initial fluid to test GI tolerance in post-op patients or babies recovering from NEC or ileus.

Pedialyte is essentially D2.5W with 45 meq/L Na and 20 meq/L K. (The anions are chloride (35 meq/L) and citrate (30 meq/L).) It has an osmolarity of 250 mOsm/L and provides 10 kcal/oz.

FORMULA COMPOSITIONS

Nutrient

Energy

(kcal/oz)

Protein

(g/dL)

Carbohydrates

(g/dL)

Calcium

 (mg/dL)

Phosphorus

 (mg/dL)

Sodium

 (meq/dL)

Potassium

 (meq/dL)

Iron

 (mg/dL)

Osmolarity

 (mOsm/L)

Some of this information is also available in the 2001 NICU Manual pgs. 7-5 and 7-6.

References:

American Academy of Pediatrics. "Formula Feeding of Term Infants." Pediatric Nutrition Handbook, 4^th ed. 1998. pgs. 29-42.

Aiges H. Formulae Odds and Ends. Pediatrics in Review 1997; 18: 84-5.

Tubman TRJ, Thompson SW. Glutamine supplementation for prevention of morbidity in preterm infants. Cochrane Database of Systematic Reveiws.   http://www.nichd.nih.gov/cochraneneonatal/tubman/tubman.HTM

Young TE, Mangrum OB. Neofax 2001: A Manual of Drugs Used in Neonatal Care, 14^th ed. Acorn Publishing. Pgs. 209-244.