Background: It has been much debated whether fatty acid composition of human milk differs after preterm as compared to full-term delivery.
Subjects and methods: Human milk samples were obtained from mothers of preterm (n = 8, gestational age: 28.0 [4.2] weeks, birthweight: 1,235 [420] g, median [interquartile range]) and full-term (n = 10, gestational age: 38.5 [2.7] weeks, birthweight: 3375 [282] g) infants every day during the first week and thereafter on the 14th, 21st, and 28th day of lactation. Fatty acid composition was measured by high-resolution capillary gas-liquid chromatography.
Results: Maternal age and body mass index did not differ, and food frequency questionnaire did not reveal significant differences in diet between the two groups. Fat contents of human milk did not differ between the two groups. Values of linoleic acid (C18:2n-6) and alpha-linolenic acid (C18:3n-3) did not differ throughout the study. Values of the metabolites C18:3n-6 and C20:3n-6 as well as C18:4n-3 and C20:3n-3 were significantly higher after preterm as compared with full-term delivery. Values of arachidonic acid (C20:4n-6; e.g., day 4: 0.82 [0.4] vs. 0.44 [0.28]; day 7: 0.61 [0.25] vs. 0.34 [0.25]; day 21: 0.33 [0.18] vs. 0.44 [0.44]; in weight percent, preterm versus full-term, P < 0.05) and docosahexaenoic acid (C22:6n-3; e.g., day 4: 0.33 [0.23] vs. 0.15 [0.14]; day 7: 0.26 [0.16] vs. 0.13 [0.15]; day 21: 0.11 [0.08] vs. 0.21 [0.17]; P < 0.05) were significantly higher in human milk samples of mothers of preterm as compared with full-term infants.
Conclusion: In this study, percentage contributions of arachidonic and docosahexaenoic acids as well as the those of the intermediary metabolites of essential fatty acid metabolism were all significantly higher in early human milk samples of mothers giving birth to very low birth weight preterm as compared with full-term infants.