Lactoferrin levels in term and preterm milk

Even though there is no doubt that human milk is the best nourishment for the neonate, there is still controversy regarding its suitability for preterm infants. The aim of this study was to contribute to the knowledge of the anti-infective properties of preterm milk, measuring lactoferrin levels, which are a non-specific protective factor.

Samples from 26 preterm and 20 term mothers (mean gestational age +/- standard deviation, 30.9+/-2.6 and 39.5+/-1.1 weeks, respectively) were collected during the first month post-partum. Milk samples were obtained by total expression of one breast between 10 a.m. and noon. An aliquot was kept at -20 degrees C until analyzed by SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Each sample was run in duplicate.

Lactoferrin levels (X +/- SD) in colostrum and mature milk varied from 575.0+/-218.2 mg/dL to 459.4+/-190.7 mg/dL in preterm samples and from 970.6+/-288.6 mg/dL to 292.0+/-167.4 mg/dL in term samples. No significant differences were observed between preterm and term groups, in spite of the trend observed in colostrum, where term milk tended to show higher levels than preterm milk. Decreasing values were observed in both groups along time (ANOVA, p<0.05). However, in the preterm group, lactoferrin levels seemed to maintain rather constant values from the eighth post-partum day onwards.

The trend to higher levels of lactoferrin in preterm mature milk would allow maintenance of the protective effect of human milk in preterm infants in spite of the small volumes ingested by these neonates. These findings support the practice of feeding premature infants with their own mothers' milk at a time when their immune systems have not completely developed.