Objective: To measure fetal and maternal plasma homocysteine (Hcy) concentrations in uncomplicated pregnancies.
Methods: Paired maternal venous and fetal umbilical cord blood (n = 81) samples were evaluated for plasma Hcy and vitamin B12 levels, in addition to eight neonatal umbilical cord blood samples obtained immediately following delivery.
Results: Both fetal and maternal Hcy concentrations were positively correlated with advancing gestational age (ρ = 0.44, p < 0.0001; and ρ = 0.27, p < 0.05, respectively). Fetal plasma Hcy concentrations [2.2 µmol/l (IQR: 2.0-3.2)] were significantly lower than both neonatal umbilical vein [5.0 µmol/l (IQR: 4.4-6.5); p < 0.001] and maternal plasma Hcy levels [4.4 μmo/l (IQR: 3.4-5.4); p < 0.001]. In addition, Hcy values at term were higher in the umbilical vein compared with the umbilical artery [5.0 μmol/l (IQR: 3.4-5.4) versus 4.2 μmol/l (IQR: 3.7-5.5), respectively; p = 0.016]. Significant correlation was noted and between fetal and maternal Hcy levels (ρ = 0.50, p < 0.0001), while fetal Hcy was negatively correlated with maternal B12 concentrations (ρ = -0.32, p < 0.001).
Conclusions: Fetal Hcy levels were significantly lower than maternal and neonatal levels and correlated with gestational age across the second half of pregnancy.
Keywords: Fetal blood; homocysteine; maternal blood; vitamin B.