PLASMA ADENOSINE CONCENTRATION IN APPROPRIATE-FOR-GESTATIONAL-AGE ANDSMALL-FOR-GESTATIONAL-AGE FETUSES

OBJECTIVE: Our purpose in this study was to investigate the relationsh ip between fetal plasma adenosine concentration and catecholamine conc entration, blood gases, and pH in appropriate- and small-for-gestation al-age fetuses. STUDY DESIGN: Cordocentesis was performed in 23 approp riate- and 14 small-for-gestational-age fetuses at 30 to 37 weeks' ges tation for the measurement of umbilical venous blood plasma adenosine and catecholamine concentrations, blood gases, and pH. RESULTS: In sma ll-for-gestational-age fetuses plasma adenosine concentration was high er, umbilical Venous Po-2 and pH were lower, and Pco(2), was significa ntly higher than in appropriate-for-gestational-age fetuses. The eleva tion of plasma adenosine concentration was inversely related to umbili cal venous Po-2 and pH. CONCLUSION: Some small-for-gestational-age fet uses are exposed to diminished oxygen tension and acidotic blood gas v alues in utero. We postulate that the acompanying elevation of plasma adenosine may elicit protective adaptation during fetal asphyxia as a stress response.