Amino acids, glucose and lactate concentrations in umbilical cord blood in relation to umbilical artery flow patterns

To study possible relationships between abnormal placental perfusion, hypoxemia and impaired fetal nutrient supply.

Umbilical artery flow velocity waveforms were assessed in high risk pregnancies and compared with controls. Three groups were studied. In group I (n = 13) the pulsatility index (PI) was within normal limits, in group II (n = 9) PI was > 2 S.D. in the presence of positive end diastolic velocities and in group III (n = 13) end diastolic velocities were absent. pH and PO2 levels and concentrations of amino acids, glucose and lactate were measured in umbilical blood obtained at cesarean section (n = 35).

An inverse correlation was found between concentrations of essential amino acids concentrations and the pulsatility index in the umbilical artery (P = 0.03). No correlation with hypoxemia was found (P = 0.32). The glycine/valine ratio was significantly increased in the groups with abnormal Doppler velocity indices (P = 0.02). Glucose concentrations were significantly reduced in the case of absent end diastolic velocities (P = 0.001). No significant differences were found between the three groups concerning lactate concentrations and acid-base balance parameters.

These findings, especially the increased glycine/valine ratio, which is characteristic for kwashiorkor, indicate that abnormal placental perfusion is associated with impaired fetal nutrient supply, in the presence of a normal fetal oxygenation.