Placental hexokinase activity is related to fetal blood flow distribution in a cross-sectional study of healthy human pregnancies at term.

OBJECTIVE

Given that placental hexokinase is a key enzyme in glucose metabolism, we hypothesized that placental hexokinase activity is related to fetal blood flow distribution in healthy pregnancies with scheduled cesarean delivery at term.

METHODS

We included sixty-seven healthy pregnant women at term. Blood flow in the maternal uterine artery, umbilical vein, and ductus venosus was measured by Doppler ultrasound. Blood samples from the maternal radial artery and uterine vein, and umbilical artery and vein were collected at scheduled cesarean section, and glucose and insulin concentrations were measured. Placental tissue hexokinase activity was measured by a commercially available assay. Spearman's correlation analyses were performed between placental hexokinase activity and fetal blood flow in different vessels with and without normalization for birthweight.

RESULTS

Placental hexokinase activity was positively correlated with ductus venosus blood flow (ρ = 0.39, p = 0.001; ρ = 0.38, p = 0.001) and ductus venosus shunting fraction (ρ = 0.38, p = 0.001; ρ = 0.32, p = 0.009) in the crude analyses and when normalized for birthweight. A negative correlation was observed between placental hexokinase activity and fetal liver blood flow when normalized for birthweight (ρ = -0.25, p = 0.04). Birthweight-based tertile analyses showed that placental hexokinase activity was positively correlated with ductus venosus shunting fraction without and with normalization for birthweight in the lower (ρ = 0.48, p = 0.02, ρ = 0.48, p = 0.02) and upper (ρ = 0.59, p = 0.004; ρ = 0.61, p = 0.002) birthweight tertiles. Placental hexokinase activity showed a positive correlation with ductus venosus blood flow (ρ = 0.47, p = 0.03) only when normalized for birthweight in the upper birthweight tertile.

CONCLUSION

This study suggests that placental glucose metabolism and the distribution of fetal umbilical blood flow are interrelated in healthy pregnancies.