Comparison of the Effect of Direct Breastfeeding, Expressed Human Milk, and Infant Formula Feeding on Infant Weight Trajectories: A Systematic Review

Background: Formula and breastfeeding are known factors associated with infant weight trajectories. Evidence exploring the effect of expressed human milk feeding on infant weight in the community setting has not been well synthesized. Objectives: This systematic review examined (1) weight changes among infants fed expressed human milk and (2) differences in weight change between infants fed expressed human milk and infants fed at the breast or infant formula via bottle. Methods: A comprehensive search of the literature was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The quality of each study was appraised using the Joanna Briggs Critical Appraisal Tools. Results: A total of six studies met the eligibility criteria and included a total of 5,152 infants. The within-subject analysis identified only 31 infants strictly or predominantly fed expressed human milk. The between-subject analysis comparing expressed human milk feeding to the available comparison groups (formula-fed or direct at the breastfed) revealed that higher weight gains were observed in the weight trajectories among infants in the bottle or formula-fed conditions in four of the six included studies. Conclusions: Findings from the few studies included in this review found a difference in the infant weight gain patterns among expressed human milk-fed infants when compared with their respective feeding groups (directly breastfed or formula-fed). Further research is needed to corroborate these findings and elucidate the clinical significance of the differences in weight gain patterns observed across infant feeding groups.