Infant Formulas

Preterm Formulas for Use in Hospitals

It is seldom appropriate to use products designed to meet the needs of VLBW infants in the hospital after initial discharge unless they are sent home when they weigh less than 2.5 kg. Preterm formulas such as Similar Special Care with Iron 24 and Enfamil Premature 24 with Iron have been designed to provide an energy-dense feeding with higher concentrations of vitamins and minerals. These products meet the increased needs of preterm infants who take smaller volumes of milk than full-term infants.

Although some preterm infants may have increased need for calcium and phosphorus after discharge, continuation of preterm formula for infants who weigh more than 2.5 kg will lead to increased intakes of several vitamins, including vitamin A and D. It is unclear how long it is safe to use these products secondary to an increased intake of these vitamins (see section on Supplements). The same issues pertain to extended use of breast milk fortifiers. Case reports of hypervitaminosis D in larger infants using preterm products suggest that these products should be discontinued when the infant is exceeding the recommended intakes for fat soluble vitamins (2.5-3.0 kg). Continued use of highly fortified preterm formulas or breastmilk fortifiers should be reserved for those infants with osteopenia. Infants on these formulas should have careful monitoring of vitamin D, calcium and phosphorus status.

Preterm Post-Discharge Formulas

Nutrient dense formulas have been developed for feeding the preterm infant after hospital discharge. NeoSure (formerly NeoCare) from Abbott and Enfamil 22 from Mead Johnson are transitional formulas designed to provide an energy-dense feeding which is higher in protein and some vitamins and minerals. These formulas may be mixed to 22 or 24 kcal per ounce. Although some studies demonstrate improved growth in preterm infants fed these formulas after discharge compared to infants fed a standard formula (Lucas 1992, Friel 1993, Carver 2001), other studies do not demonstrate similar growth advantages (Chan 1994, Wheeler 1996, Lucas 2001, Koo 2006). Cost, availability, and individual nutrient requirements should be considered in choice of formula for preterm infants after hospital discharge As vitamin content of these formulas is higher than standard infant formulas, care should be take when supplemental vitamins are provided. In general, supplemental vitamins should be discontinued when intake of formula mixed to 22 kcal/oz is 20 ounces per day.

Standard Cow's Milk-Based Formulas for VLBW Infants

Standard iron-fortified, cow's milk-based infant formula may be recommended for infants who have achieved a weight of 2-2.5 kg and are not receiving their own mother's milk. The standard preparation method for these products makes a formula that has 20 kcal/oz. Infants being prepared for discharge may be transitioned from a 24 kcal/oz product used in the hospital to a formula with a density of 20 kcal/oz. This is often done in the last days of hospitalization and it can be difficult for some infants to maintain adequate intake after discharge on a 20 kcal/oz formula.

In order to achieve an intake of >120 kcal/kg/d the infant must be able to consume a total of more than 180 cc/kg/d or 2.7 oz/lb. The following table provides indications of the total intake that might be required to meet energy needs with formulas mixed at both 20 and 24 kcal/oz.

Some infants may benefit from higher caloric density formula through the first weeks and months at home. Those who are transitioned from a higher density formula to 20 kcal/oz formula should be carefully monitored to see if standard formula density can support adequate growth. More information can be found in the section on concentrating formula and in the decision tree for changing formula concentration.

Standard infant formulas are designed to meet the DRI for term infants when the infant consumes approximately 32 oz/day. Infants between 2.5 - 4 kg (5.5 - 8.8 lbs.) generally do not consume this volume and need a multivitamin supplement to meet the DRI (See section on supplements).

Soy Formulas

Soy formulas are not recommended for feeding preterm infants because of the decreased bioavailability of calcium and phosphorus in these products. Hypophosphatemia has been reported in full-term infants. Preterm infants are at increased risk for alteration in bone mineralization and the incidence of hypophosphatemic rickets is higher in this population. For further discussion of this issue, see the American Academy of Pediatrics Position Statement on the Use of Soy Formulas: http://www.aap.org/policy/re9806.html .

Hydrolyzed Whey-Based Formulas
(Adapted from Hattner, 1994)

Whey hydrolysate formulas can be used with VLBW infants in place of standard cow's milk formula, with the same caveats.

In this product, the whey fraction of cow's milk protein has been broken down by enzyme hydrolysis to yield smaller protein fractions, making it less allergenic than the whole proteins of regular formulas.

Casein Hydrolysate Formulas
(Adapted from Hattner, 1994)

Casein hydrolysate formulas may be used with VLBW infants who have special needs. They tend to be expensive and should be used only when truly needed.

Nutramigen, Pregestimil, and Alimentum are formulas based on a hypoallergenic protein source consisting of amino acids and small peptides. They are useful when there has been damage to an infant's GI tract from a viral or bacterial infection or complications of prematurity such as NEC.

These products may be appropriate if an infant presents with malabsorption. With significant fat malabsorption, Pregestimil or Alimentum may be the products of choice because about half of the fat is provided by MCT (medium chain triglycerides), which do not require the normal fat digestive pathways.

It has been suggested that these products might be useful during times of acute GI infection as well. A damaged GI tract is permeable to foreign proteins, predisposing the infant to an allergic condition. Use of casein hydrolysates may improve digestion and allow for mucosal healing and recovery of function. This would allow a progressive return to more standard formulas.

Amino Acid-Based Formulas

Some infants will have difficulties with even casein hydrolysate formulas and may require amino acid-based formulas. Neocate is the only formula of this type on the market at this time. This product is designed for infants who have multiple food protein intolerances. Use of Neocate has not been studied in VLBW infants.

Formulas for Older Children

There are a number of pediatric formulas appropriate for children beyond one year of age, who have reached 10 kilograms or more and require continued nutrition intervention. Nutrient-dense formulas are available for oral and tube feeding use. Additionally, modified protein based formulas are available for children. Content information can be found at their respective product websites.

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