Background Human milk (HM) is unique and the gold standard for feeding preterm infants. However, HM contains insufficient quantity of energy, calcium, phosphorus and protein - the key nutrient - for preterm infants. Low protein intake is associated with poor weight gain, length and neurocognitive outcomes. Therefore, human milk fortifiers have been developed. The aim of Compo-HMA study was to measure the composition and variation in preterm HM, the impact of lactation period and different milk processing types on the nutritional content with MIRIS Human Milk Analyzer (HMA).

Methods HM was taken from mothers of premature infants born with a birthweight <1500 g and a gestational age <32 weeks. Protein, fat, lactose and energy composition was measured with MIRIS HMA subjected to different milk processing types fresh/fresh pasteurised/thawed/thawed pasteurised. Furthermore, the relation between protein content and lactation days has been evaluated.

Results Native HM (n = 83) contained in mean 1.1 ± 0.37 g protein, 3.2 ± 0.85 g fat, 6.6 ± 0.34 g lactose and 59.8 ± 10.65 kcal energy/100 ml HM. Maximum variation was observed in protein content with 0.2–2.2 g/100 ml HM. Lactation day correlated significantly with protein content (p < 0.0001; r = -,4243). Processing of HM had no effects on protein-or nutritional level.

Conclusions Variations in macronutrients from mother to mother are high, particularly in protein. Protein significantly decreased with lactation period. Various conditions of HM processing had no effect on measured nutritional content. MIRIS is an adjuvant tool to provide actual nutrient composition of HM. The results indicate that HM analysis is important for individualised fortification and improves the nutritional management of premature infants.