The Volume of Breast Milk Intake in Infants and Young Children: A Systematic Review and Meta-Analysis

Objective: The objective of this study was to provide global breast milk intake estimates for infants and children from 0 to 3 years old. Materials and Methods: A systematic search of online databases (Embase, MEDLINE, and CENTRAL) was conducted and complemented with a manual search of additional databases (African Journals Online and LILACS), reference lists, and unpublished data. Studies with apparently healthy mothers and their children 0-3 years old worldwide were included. Random effects meta-analyses, subgroup analyses, and meta-regressions were conducted. Results: A total of 167 studies on breast milk intake were identified. The mean daily breast milk intake among all the studies included was 670 mL per day and 117 mL/kg per day. Breast milk intake was influenced by infant age, infant body weight, and breastfeeding practices. The deuterium dilution method tended to yield higher estimates than test-weighing methods. Breast milk intake over time was modeled with a nonlinear meta-regression: breast milk intake (mL/day) = 51-1.4 × days +180 × log(days). When restricting to studies involving healthy term infants exclusively breastfed up to 6 months, breast milk intake was 624 mL per day and 135 mL/kg per day at 1 month, 735 mL per day and 126 mL/kg per day at 3 months, 729 mL per day and 107 mL/kg per day at 6 months, and 593 mL per day and 61 mL/kg per day at 12 months. Conclusions: This review provides global breast milk intake estimates for infants and young children. It demonstrates differences in intakes according to region and measurement method, as well as longitudinal changes over the first year of life.