The relationship of hypoxia to hypoxanthine concentration during pregnancy and delivery.

The concentration of hypoxanthine in plasma was suggested as an indicator of hypoxic conditions in newborns. We examined the concentration of hypoxanthine in maternal venous as well as in umbilical cord blood during pregnancy and during and after labor. The concentration of hypoxanthine in the cubital venous blood of nonpregnant healthy women and in healthy pregnant women and in women with complicated pregnancies was the similar. During birth there is an increase of the hypoxanthine concentration in maternal blood. This could be caused by the muscular work involved in giving birth (contraction, pushing, breathing). The values increased from 2.0-4.1 mumol/l in normal and abnormal pregnancy up to values of 9.4-11.8 mumol/l immediately after delivery. At the end of delivery the level of hypoxanthine is higher in the venous blood of the mother than in the umbilical blood. The concentration of hypoxanthine in umbilical venous blood and umbilical arterial blood did not show any significant differences. When clinical symptoms of hypoxia (depressed state of the neonate, high Thiringer asphyxia score, low Apgar score) were observed in the neonate, the hypoxanthine concentration in the umbilical vessels was increased (normal 4.7 mumol(l; slightly depressed 7.6 mumol/l, severely depressed 10 mumol/l).