Human Milk Analyser shows that the lactation period affects protein levels in preterm breastmilk.

AIM: This study measured the composition of preterm human breastmilk, particularly the protein content, with the MIRIS Human Milk Analyser, compared our results with published values and determined the relationship between protein content and lactation period. METHODS: We analysed 83 samples of 24-hour pooled human milk from 76 mothers who delivered preterm infants weighing under 1500 g at less than 32 weeks of gestational age. The milk's protein, fat and energy were measured by the MIRIS Human Milk Analyser and compared to reference values. The relationship between protein content and lactation period was quantified. RESULTS: On average, the samples contained 1.1 ± 0.37 g (0.2-2.2 g) of protein, 3.2 ± 0.85 g (range 1.1-6.1 g) of fat, 6.6 ± 0.34 g of lactose (5.5-8.0 g) and 60 ± 11 kcal (39-94 kcal) of energy per 100 mL. The wide variations in macronutrient content were not influenced by the gestational age of the infant and the lactation day results from 70 of the mothers correlated inversely with the protein content (p < 0.0001; r = -0.42). The MIRIS proved useful, but some adjustments are needed. CONCLUSION: Variations in macronutrients were high in the breastmilk of women who delivered preterm babies and the protein content decreased with lactation. With adjustments, the MIRIS might provide a helpful tool for individualised fortification.

Effect of fortifiers and additional protein on the osmolarity of human milk: is it still safe for the premature infant?

OBJECTIVES: The present guidelines of the American Academy of Pediatrics recommend that osmolarity not exceed 450 mOsm/kg (or approximately an osmolarity of 400 mOsm/L) for breast milk or infant formulae, to minimize the risk factors for necrotizing enterocolitis. A commercial protein supplement has been developed to meet special protein requirements (4.0-4.5 g · kg(-1) · day(-1)) of infants with a birth weight <1000 g. Because its effect on osmolarity has not been systematically studied, we characterized the effects of fortification on the osmolarity of human milk (HM). METHODS: Osmolarity of fresh and processed HM was measured at baseline, after fortification with a commercial HM fortifier and after further supplementation with additional protein increasing in 0.5-g steps up to 4.0 g. Measurements were performed immediately after adding fortifier and/or protein and after 24 hours. In addition, changes in osmolarity were determined after adding therapeutic additives such as iron, multivitamin supplement, and calcium-phosphorus capsules. RESULTS: Native HM samples (n = 84) had 297 mOsm/L, (median; 95% confidence interval 295-299 mOsm/L). Adding HM fortifier increased osmolarity up to 436 mOsm/L (95% confidence interval 431-441 mOsm/L). Additional protein supplementation increased osmolarity by 23.5 mOsm/L per 0.5-g step, up to a maximum of 605 mOsm/L. Pasteurization decreased osmolarity by 20-30 mOsm/L (P < 0.001), and storage for 24 hours slightly increased osmolarity (by 11.5 mOsm/L P = 0.0002). Therapeutic additives increased osmolarity up to 868 mOsm/L. CONCLUSIONS: Adding HM fortifier and additional protein to HM increased osmolarity to >400 mOsm/L and therefore above the recommended threshold. Because of the excessive increase in osmolarity combinations of HM + fortifier and additional protein should not be applied together with multivitamins or other additives.