[Nitrogen fractions of human milk during the first week of lactation. Comparison of milk from mothers of term and premature newborn infants].

Nitrogen fractions in human milk (total nitrogen, non protein nitrogen, casein nitrogen and soluble protein nitrogen) were determined by direct dosage or by calculation during the first 7 days of lactation in 61 mothers feeding artificially. Twenty-five delivered at term and 36 prematurely. In all cases a decrease in all nitrogen fractions was observed. The amounts of total nitrogen and soluble proteins were similar in both groups. A difference in the distribution of the nitrogen fractions occurs only on the 8th day following delivery. Milk from mothers who deliver prematurely contains more casein and less non protein nitrogen amounts.