The effect of race and supplementation on maternal and umbilical cord plasma folates.

Objective: The purpose of this study is to test the hypothesis that race and supplementation affect the concentration and correlation of various folate species in maternal and umbilical cord blood.

Methods: This is a single-center, prospective, cross-sectional cohort of cord blood samples obtained from 40 uncomplicated term pregnancies as a pilot study, following a protocol approved by the Institutional Review Board. High performance liquid chromatography mass spectrometry quantitated the following concentrations in extracted plasma samples: 5-methyltetrahydrofolate (5MTHF), 5,10-methenyl-tetrahydrofolate (5,10-MeTHF), tetrahydrofolate (THF), and unmetabolized folic acid.

Results: Folate concentrations in the umbilical cord plasma were consistently higher than maternal samples for 5MTHF ( < .001), 5,10-MeTHF ( < .001), and THF ( < .001); cord blood folic acid levels, however, were lower than maternal samples ( < .03). While 5MTHF was the most prevalent folate, ratios comparing cord blood to maternal blood folates suggests a fourfold preponderance of THF in cord blood folate signature, a trend unchanged by supplementation. Prenatal supplementation increased the concentrations of 5MTHF, for both maternal ( < .01) and cord blood samples ( < .005). In comparison to the other two racial groups, African American 5MTHF concentration demonstrated a lower total folate concentration in both maternal samples and cord blood samples, in addition to a relatively blunted response to supplementation. A significantly positive correlation between maternal and cord blood 5MTHF concentration was noted in all three racial groups. Supplementation resulted in a positive correlation between maternal and cord blood 5MTHF concentrations ( = 0.85,  < .0001).

Conclusions: 5MTHF is the most prevalent folate in both cord and maternal plasma, and race and supplementation primarily affect variations in maternal and fetal 5MTHF concentrations and their correlation with each other. However, the greater concentration of THF in cord blood relative to maternal blood offers preliminary insight into the importance of how folate metabolism differs in the specific context of fetal development and physiology, with greater emphasis on DNA synthesis and stability. Furthermore, supplementation appeared to not have as great an impact on African American maternal or cord blood folates, suggesting a variable benefit of current repletion strategies to certain subsets of the population. Future studies that further elucidate these differences and their impact on birth outcomes may help inform supplementation protocols that are more personalized, with greater efficacy in promoting positive perinatal outcomes.