REVIEW QUESTION

Is formula or donor breast milk more beneficial for the growth and development of preterm or low-birth-weight infants when maternal breast milk is not available?

TYPE OF REVIEW

A systematic review of 12 trials with a total of 1,871 participants.

RELEVANCE FOR NURSING

The growth and development of preterm or low-birth-weight infants can be challenged by gastrointestinal immaturity. Immature gut function and inflammatory response in preterm infants are associated with invasive infections, including necrotizing enterocolitis (NEC). Early diagnosis remains difficult, and diagnosis is often too late to prevent infant mortality or ongoing neurodevelopmental disability. For nurses working in the special care nursery, decreasing risk of infection by establishing progressive infant feeding, preferably using maternal breast milk, is the preferred route to sustained growth and development.

Fresh breast milk is the best source of naturally occurring immunoglobulins, which inhibit harmful bacterial colonization in the infant gut, instead promoting effective absorption of nutrients and gut maturity. Where fresh breast milk is insufficient or unavailable, donor milk is considered the next best choice despite its reduced antiinflammatory benefits, followed by substitute artificial milk (preterm formula), which has no antiinflammatory benefits but measurable nutrition.

CHARACTERISTICS OF THE EVIDENCE

The objective of this review was to assess the effectiveness of infant formula versus breast milk (fortified or not) on the rates of growth and development in preterm or low-birth-weight infants in special care nurseries.

Inclusion criteria were randomized controlled trials (RCTs) and cluster RCTs of infants younger than 37 weeks' gestation or weighing less than 2,500 g at birth in special care nurseries. Interventions were enteral or parenteral feeding methods using formula or donor breast milk. The primary outcomes were short- and long-term growth, including time to regain birth weight and developmental markers assessed at six months corrected age; and neurodevelopment, including developmental delay and disability assessed from 12 months corrected age. Secondary outcomes were mortality, confirmed NEC, time to establish full enteral feeding, feeding intolerance, and invasive infections.

The review included 12 trials with a total of 1,879 participants. Four trials compared standard term formula with unfortified donor breast milk, both as the sole diet; and eight trials compared preterm formula with donor breast milk, either used alone or supplementary to maternal breast milk (in four trials the breast milk was fortified). It wasn't possible to determine conclusively that formula-fed infants regained birth weight sooner than those fed donor milk. Only three trials reported faster weight gain with formula, two reported no significant difference, and others did not measure time to regain birth weight.

In nine trials, rates of hospital weight gain were higher in formula-fed infants than in those fed donor milk (moderate certainty). Greater differences were reported between preterm formula use and unfortified donor milk. Nine trials determined with moderate certainty that formula-fed infants were at a higher risk for NEC.

BEST PRACTICE RECOMMENDATIONS

Special care nursery infants fed preterm formula regained birth weight sooner and had higher rates of consistent weight gain than infants given term formula or donor breast milk. However, preterm or low-birth-weight infants fed formula rather than donor milk had significantly increased incidences of NEC.

Although preterm formula provides quicker initial weight gain and developmental growth in preterm and low-birth-weight infants than donor milk, the increased incidence of NEC requires consideration prior to clinical decision-making.

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