Expressing breast milk at home for 24-h periods provides viable samples for macronutrient analysis

This study aimed to evaluate the reproducibility of macronutrient measurements of domestic pooled human milk from mothers with preterm infants and to see how the results affected human milk fortifications.

We asked 28 new mothers to express their breast milk for 24 h on two consecutive days and repeat the process at weekly intervals. The samples were analysed using mid-infrared technology to calculate the differences between the milk collected on two consecutive days for reproducibility and the total protein supply with standard fortification.

There was a significant linear correlation between the two consecutive days with regard to protein (r = 0.94, p < 0.001), lipids (r = 0.86, p < 0.001), lactose (r = 0.91, p < 0.001) and 24-h volume (r = 0.96, p < 0.001). The percentage of the samples that would provide a protein supply of 3.5-4.5 g/kg/d with a fortification of 0.6 and 1.2 g protein/100 mL at a volume of 170 mL/kg were 28% and 41%, respectively.

The domestic pooling of 24-h expressed human milk for macronutrient analysis was a simple and reliable way of obtaining representative data. Standard fortification implies there is a risk of under- and over-nutrition, and individual fortification may improve the nutrition of preterm infants.