Formula milk versus donor breast milk for feeding preterm or low birth weight infants.

Eight randomized or quasi-random controlled trials; total 1017 infants. Participants: preterm and/or low birth weight infants; most clinically stable; gestational age <32 weeks and/or birth weight <1800 g; exclusions included small for gestational age at birth and congenital anomalies or GI/neurological problems.

Regimens compared: enteral feeding with formula milk (term or preterm) versus donor breast milk. Term formula: ~67–70 kcal/100 mL; Preterm formula: up to ~80 kcal/100 mL. Donor breast milk: pasteurized in all trials except Tyson 1983; most trials used donor milk without nutrient fortification (Schanler 2005 as exception). In several trials, formula or donor milk was used as a sole diet; in others as a supplement to maternal expressed breast milk. Caloric parity aimed by giving donor milk at 170 mL/kg/day versus formula at 150 mL/kg/day; feeds advanced to 160–200 mL/kg/day with fortification as needed to support weight gain. First week: small quantities of mother’s own milk (~20 mL/kg/day) were given and then volume increased; fortification with human milk fortifier when indicated.

Formula milk increased short-term growth compared with donor breast milk but raised risk of necrotising enterocolitis (NEC). Time to regain birth weight about 4 days sooner with formula (-4.0 days; 95% CI -5.8 to -2.2). Weight gain rate +2.6 g/kg/day (95% CI 2.0–3.2). Crown-heel length +1.1 mm/week (95% CI 0.6–1.7). Head circumference +1.2 mm/week (95% CI 0.7–1.7). NEC incidence higher with formula (RR 2.5; 95% CI 1.2–5.1; RD 0.03; NNH 33). No significant differences in mortality or long-term growth/development. Subgroup analyses suggest larger growth effects with preterm formula; long-term outcomes similar. Limitations include reliance on older, largely unfortified donor milk regimens and lack of blinding; applicability to current fortified-donor-milk practice is limited. More trials are needed comparing formula with nutrient-fortified donor breast milk and addressing sole-diet versus supplement contexts; blinding should be improved to reduce bias.

Older trials with heterogeneous regimens; donor milk often not fortified (except Schanler 2005); variations in formulas and donor milk types; limited blinding and potential detection bias; not all trials reported long-term outcomes; generalizability to fortified-donor-milk practice and diverse settings may be limited.