The b-G activity in the intestinal mucosae has been related to jaundice etiopathogeny in the newborn, but the importance of this activity in human milk remains doubtful. The aim of this study was to describe the evolution and inter-relation between the b-G levels in human milk and plasma from mothers of adequate (AGA) and small for age (SGA) term newborns in the 2nd and 7th days of life, as well as to analyse the relationship of these results with the presence of jaundice.

b-G levels were evaluated in human milk and plasma of 42 mothers, 2 and 7 days after delivery. Were excluded all cases of hemolytic disease, hematomas or plethora. Jaundice was evaluated in the 2nd day of life. Statistical analysis was by t-test and Pearson correlation, significance was set at 0.05.Table

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The b-G activity decreased from the 2nd to the 7th day in human milk(p=0.02) and plasma (p<0.001), with significant smaller plasma than milk levels only in the 2nd day (p=0.003). There were no differences between the milk and plasma b-G activity in the 2nd and 7th day among the two groups. There was a positive correlation between milk and plasma b-G levels in the 2nd day (r=0.60; p<0.001). There was no relationship between the levels of b-G in the 2nd day and jaundice.

We conclude that the presence of intra-uterine growth retardation did not modify the milk and plasma b-G levels. This activity was lower in the plasma than in human milk as well as it was smaller in the end of the first week, suggesting a secretion of this enzyme from plasma to milk.