[Variations in the concentration of total human milk proteins in the first month of lactation].

Introduction: Human milk proteins are maximally adapted to physiological needs of a neonate. Thus, depending on the speed of the neonatal growth and development, the content of milk proteins changes, both in quantity and quality.

Objective: The study was conducted in order to determine variations of total protein concentrations in milk in the first and third lactation week in lactating mothers of term and preterm neonates. Also, we analyzed the influence of the mode of delivery, neonatal Apgar score and parity on the concentration of human milk proteins in both lactation phases.

Method: The study aims were evaluated on the sample of 48 women, of whom 33 were mothers of term neonates and 15 of neonates born between the 34th to 37th gestational weeks. Total protein level of the lactation milk from the middle phase was determined using the standard laboratory method (Lowry et al., 1951), and the obtained differences were analyzed by t-test.

Results: Total protein concentration in term colostrum was 17.60-45.17 g/l (X = 24.71 +/- 5.19), while in preterm colostrum it was 28.39-73.30 g/l (X = 39.17 +/- 11.08). The total protein level of mature milk in women who had term delivery was 11.90-22.11 g/l (X = 16.39 +/- 2.96), while in women who had preterm delivery it was 14.50-44.19 g/l (X = 23.25 +/-8.96). The obtained results indicated that total protein concentration in women who had preterm delivery was significantly higher than that of women who had term delivery, both in the colostral and mature phase of lactation. (p < 0.01). Also, the difference in the protein concentration was statistically highly significant (p < 0.01) in the colostral and mature phase of lactation, both in women who had term and preterm delivery. Variations in the total protein level of human milk were not significant, depending on the prematurity stage, the mode and severity of delivery and parity, both in the first and third week of lactation.

Conclusion: Our results show that total protein concentration in human milk was significantly higher in the first than the third week of lactation. In both lactation phases, milk protein content was higher in women who had preterm delivery than those having had term delivery. The influence of prematurity stage, the mode and severity of delivery and parity on the total milk protein level was not significant.