Plasma adenosine concentration in appropriate- and small-for-gestational-age fetuses.

Abstract

Our purpose in this study was to investigate the relationship between fetal plasma adenosine concentration and catecholamine concentration, blood gases, and pH in appropriate- and small-for-gestational-age fetuses. Cordocentesis was performed in 23 appropriate- and 14 small-for-gestational-age fetuses at 30 to 37 weeks' gestation for the measurement of umbilical venous blood plasma adenosine and catecholamine concentrations, blood gases, and pH. In small-for-gestational-age fetuses plasma adenosine concentration was higher, umbilical venous PO2 and pH were lower, and PCO2 was significantly higher than in appropriate-for-gestational-age fetuses. The elevation of plasma adenosine concentration was inversely related to umbilical venous PO2 and pH. Some small-for-gestational-age fetuses are exposed to diminished oxygen tension and acidotic blood gas values in utero. We postulate that the accompanying elevation of plasma adenosine may elicit protective adaptation during fetal asphyxia as a stress response.