Fetal and maternal concentrations of uric acid and oxypurines during labor and post partum.

Concentrations of uric acid (UA) and oxypurines (OPs) were enzymatically determined in fetal scalp plasma, amniotic fluid, and maternal venous plasma simultaneously collected during oxytocin-induced labor in 19 normal term parturient patients. Values were compared with concentrations in arterial and venous cord plasma and maternal plasma drawn immediately post partum. During labor until just before delivery fetal levels of UA were significantly lower and OP concentrations were significantly higher than the corresponding maternal levels. These differences were absent when cord and maternal concentrations were compared. It is concluded that UA and OP values in cord plasma do not reflect fetal levels during labor. The cause of this discrepancy remains obscure.