Hypoxanthine in fetal umbilical venous blood and amniotic fluid from pregnancies complicated by rhesus isoimmunization.

Concentrations of hypoxanthine (HX) was determined in umbilical venous blood and amniotic fluid obtained at 74 instances in 36 rhesus immunized patients before the onset of labor. HX concentrations were related to gestational age, concentrations of hemoglobin and lactate, pH, and partial oxygen pressure in umbilical venous blood. Multiple regression analysis revealed hemoglobin concentration to be the only variable that had any explanatory power to HX in amniotic fluid. No one of the studied variables gave any significant contribution to a regression model to explain HX in umbilical venous blood. We conclude that HX levels in umbilical venous blood and in amniotic fluid from rhesus immunized patients were not associated with fetal blood gases before the onset of labor.