Vitamin B12 and placental expression of transcobalamin in pregnant adolescents

• The first study on vitamin B12 and placental transcobalamin in pregnant adolescents.
• Maternal vitamin B12 concentrations were not significantly associated with placental TC mRNA expression or protein abundance.
• Placental TC mRNA expression was not correlated with TC protein abundance.
• Higher placental TC protein abundance was associated with higher infant cord blood vitamin B12 concentrations.

BackgroundTranscobalamin is a key placental protein involved in transport of vitamin B12 to the fetus. However, few data currently exist on the ability of the placenta to modify vitamin B12 transporter expression, particularly in high-risk populations such as pregnant adolescents.ObjectiveThis study was conducted to determine the impact of maternal and neonatal serum vitamin B12 concentrations on placental transcobalamin (TC) expression in a cohort of healthy pregnant adolescents in the United States.DesignSerum vitamin B12 concentrations were measured in maternal blood samples at mid-gestation (26.4 ± 2.8 weeks) and delivery (39.8 ± 1.4 weeks) and infant cord blood samples at birth. Placentas were collected at delivery and TC mRNA expression (ΔΔCt) and TC protein abundance (TC:α-actin) were evaluated. Linear and binomial regression models were used to examine the associations of maternal serum (mid-gestation, delivery) and cord blood vitamin B12 concentrations with placental TC mRNA expression and protein abundance (n = 63).ResultsMaternal serum vitamin B12 concentrations at mid-gestation or delivery were not significantly associated with placental TC mRNA expression or TC protein abundance (p > 0.05). Higher placental TC protein abundance was associated with increased cord blood vitamin B12 concentrations (p = 0.003).ConclusionsHigher placental TC protein abundance was associated with higher cord blood vitamin B12 concentrations, suggesting a potential role in vitamin B12 transport to the fetus.