Aim: The aim of this study was to investigate whether there is a difference in the amount of free folate that is unbound to the folate binding protein (FBP) in breast milk of preterm and term delivery groups, and the course of lactation in the first 28 days.

Materials and Methods: A total of 26 mothers were included in the study, 9 gave term, 8 gave late preterm and 9 gave preterm delivery. Colostrum (3rd day milk), transition milk (7th day milk) and mature milk (28th day milk) samples were collected from mothers. Folate levels were measured by chemiluminescent technique using Siemens ADVIA Centaur XP (Tarrytown, New York, USA) autoanalyser. No separate procedure was performed regarding FBP before the analysis and only the amount of folate unbound to the FBP was analyzed.

Results: In each delivery group, the folate levels unbound to the FBP were significantly different (p<0.001) and significantly lower in colostrum than in mature milk (p<0.001). There was a significant difference between preterm, late preterm and term delivery groups only on the 28th day (p=0.033); and the folate levels unbound to the FBP in breast milk samples of preterm delivery group was significantly higher than the term delivery group (p=0.039).

Conclusion: Folate concentrations unbound to the FBP in breast milk are at the lowest level in colostrum, contrary to the course of FBP, and increase over time during lactation to reach the highest level in mature milk. Since there was no significant difference between the preterm and term delivery groups considering the folate levels unbound to FBP in 3rd and 7th day milk samples; colostrum and transition milk would be sufficient alone for feeding of preterm delivery infants during lactation period, unless there is another problem in folate metabolism of mother or infant, and fortification may only be required for mature milk.