Effect of Freezing and Thawing on Human Milk Macronutrient and Energy Composition: A Systematic Review and Meta-Analysis

Objective: To conduct a systematic review of the effect of freezing and thawing on the macronutrient and energy composition of human milk (HM).

Design: Systematic review conducted in May 2019, including all studies reporting macronutrient and energy composition of HM, according to a search of MEDLINE, EMBASE, and Google Scholar using the key words: human milk, breast milk, macronutrients, fat, lipid, protein, carbohydrates, energy, calories, freezing, thawing, and of the references in studies identified as potentially relevant. Meta-analyses were conducted in all the studies that reported one or more of the following: total energy, true protein, fat and carbohydrates. They were reported according to following groups of freezing duration: 1-7 days, 8 -30 days, 31 days-3months, and >3 months. They were calculated and expressed as weighted averages with pooled standard deviations.

Results: 13 studies remained in the final analysis.

Conclusions: no dramatic changes in macronutrients and energy contents of milk are expected to occur within the first few months of freezing.