While breast milk appears to be superior to formula for the development of very low birthweight (VLBW) infants, it is supplemented to meet the metabolic demands of the rapidly growing premature infant. To estimate the nutritional variability of breast milk from mothers of VLBW infants, protein (bicinchoninic acid method) and fat content (creamatocrit) were measured in breast-milk spot samples from mothers of 20 VLBW infants, collected 4 times a day during the first 4 wk of lactation Protein content (median 1.9 g dl−1, range 1.1–3.5 g dl−1) and fat content (3.8/1.0–14.6 g dl−1) were highly variable and lacked a normal distribution over all samples and in individual women's milk. There was only a weak correlation between fat and protein (rs= 0.416, p < 0.001). Fat but not protein was lower in morning samples than in samples collected later in the day (p < 0.001). Protein but not fat content decreased during the weeks of lactation (rs=−0.446, p < 0.001). No impact of the baby's gestational age was observed.
Conclusion: The fat and protein content of breast milk from mothers of VLBW infants is highly variable, calling into question the clinical feasibility of individualized supplementation of breast milk for VLBW infants based on spot sample measurements.