Maternal and umbilical plasma concentrations of uric acid and oxypurines at delivery in normal and hypertensive pregnancy.

Concentrations of uric acid (UA) and oxypurines (OP) were enzymatically determined in arterial and venous cord plasma, and in maternal plasma at delivery in normal (n = 45) and hypertensive (n = 22) pregnant women. Concentrations of UA in all samples were significantly higher in hypertensive than in normal pregnancies. Concentrations of OP in hypertensive pregnancies showed a nonsignificant increase as compared with normal pregnancies. There were no significant differences between concentrations of UA or OP in paired samples of arterial or venous cord plasma and maternal plasma. This finding suggests an easy transfer of UA and OP across the placenta during labor, which is at variance with earlier experimental data obtained in the pregnant rhesus monkey. The hypothesis is put forward, that labor and delivery could influence the facility of placental transfer of UA and OP.