We hypothesized that fetal folate serum concentrations are lower and placental folate transport is impaired in pregnancies of obese women.
Umbilical vein serum and placental tissue were collected from normal weight and obese pregnant women at term. Cellular localization (immunohistochemistry) of Folate Receptor-α (FR-α), Proton Coupled Folate Transporter (PCFT), and Reduced Folate Carrier (RFC) was established. Protein expression (western blot) and transporter activity (isotope labeled methyltetrahydrofolate) were determined in syncytiotrophoblast microvillous membranes (MVM).
Fetal folate concentrations were similar in obese women as compared to normal weight women. Protein expression of FR-α in MVM was increased (+173%), RFC decreased (-41%), and PCFT unchanged. However, activity of FR-α, PCFT, and RFC was unaltered in obesity.
Fetal serum folate concentrations and placental folate transport activity are not altered in obesity at term, suggesting that limited availability of folate does not contribute to abnormal gene methylation and developmental programming.