Protein supplementation of human milk for promoting growth in preterm infants

Emma A Amissah, Julie Brown, Jane E Harding, Emma A Amissah, Julie Brown, Jane E Harding

Abstract

Background: Preterm infants require high protein intake to achieve adequate growth and development. Although breast milk feeding has many benefits for this population, the protein content is highly variable, and inadequate to support rapid infant growth. This is a 2020 update of a Cochrane Review first published in 1999.

Objectives: To determine whether protein-supplemented human milk compared with unsupplemented human milk, fed to preterm infants, improves growth, body composition, cardio-metabolic, and neurodevelopmental outcomes, without significant adverse effects.

Search methods: We used the standard search strategy of Cochrane Neonatal to search Cochrane Central Register of Controlled Trials (CENTRAL 2019, Issue 8) in the Cochrane Library and MEDLINE via PubMed on 23 August 2019. We also searched clinical trials databases and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

Selection criteria: Published and unpublished RCTs were eligible if they used random or quasi-random methods to allocate hospitalised preterm infants who were being fed human milk, to additional protein supplementation or no supplementation.

Data collection and analysis: Two review authors independently abstracted data, assessed risk of bias and the quality of evidence at the outcome level, using GRADE methodology. We performed meta-analyses, using risk ratio (RR) for dichotomous data, and mean difference (MD) for continuous data, with their respective 95% confidence intervals (CIs). We used a fixed-effect model and had planned to explore potential causes of heterogeneity via subgroup or sensitivity analyses.

Main results: We included six RCTs, involving 204 preterm infants. The risk of bias for most methodological domains was unclear as there was insufficient detail reported. Low-quality evidence showed that protein supplementation of human milk may increase in-hospital rates of growth in weight (MD 3.82 g/kg/day, 95% CI 2.94 to 4.7; five RCTs, 101 infants; I² = 73%), length (MD 0.12 cm/wk, 95% CI 0.07 to 0.17; four RCTs, 68 infants; I² = 89%), and head circumference (MD 0.06 cm/wk, 95% CI 0.01 to 0.12; four RCTs, 68 infants; I² = 84%). Protein supplementation may lead to longer hospital stays (MD 18.5 days, 95% CI 4.39 to 32.61; one RCT, 20 infants; very low-quality evidence). Very low quality evidence means that the effect of protein supplementation on the risk of feeding intolerance (RR 2.70, 95% CI 0.13 to 58.24; one RCT, 17 infants), or necrotizing enterocolitis (RR 1.11, 95% CI 0.07 to 17.12; one RCT, 76 infants) remains uncertain. No data were available about the effects of protein supplementation on neurodevelopmental outcomes.

Authors' conclusions: Low-quality evidence showed that protein supplementation of human milk, fed to preterm infants, increased short-term growth. However, the small sample sizes, low precision, and very low-quality evidence regarding duration of hospital stay, feeding intolerance, and necrotising enterocolitis precluded any conclusions about these outcomes. There were no data on outcomes after hospital discharge. Our findings may not be generalisable to low-resource settings, as none of the included studies were conducted in these settings. Since protein supplementation of human milk is now usually done as a component of multi-nutrient fortifiers, future studies should compare different amounts of protein in multi-component fortifiers, and be designed to determine the effects on duration of hospital stay and safety, as well as on long-term growth, body composition, cardio-metabolic, and neurodevelopmental outcomes.

Trial registration: ClinicalTrials.gov NCT01487928 NCT01103219.

Conflict of interest statement

EA receives a scholarship in the form of a stipend from the University of Auckland as a PhD student.

JB is currently employed by a medical writing company. The preparation of this review took place prior to this employment and her current work is not related to the topic of this review.

JH has partial salary support from research grants from the Health Research Council of New Zealand. The Council has no role in the production of this review. An undirected research grant is pending from Biomed Ltd, Auckland, New Zealand. This company makes dextrose gel.

The methods section of this review is based on a standard template used by Cochrane Neonatal.

Core editorial and administrative support for the 2020 update of this review has been provided by a grant from The Gerber Foundation. The Gerber Foundation is a separately endowed, private foundation, independent from the Gerber Products Company. The grantor has no input on the content of the review or the editorial process.