Prenatal hypoxia leads to an increased risk of adult cardiovascular disease. We have previously demonstrated a programming effect of prenatal hypoxia on the cardiac beta-adrenergic (βAR) response. The aim of this study was to determine 1) if the decrease in βAR sensitivity in prenatally hypoxic 5 week chicken hearts is linked to changes in β₁AR/β₂ARs, G_αi expression and cAMP accumulation and 2) if prenatal hypoxia has an effect on heart function in vivo. We incubated eggs in normoxia (N, 21% O₂) or hypoxia from day 0 (H, 14% O₂) and raised the post-hatchlings to 5 weeks of age. Cardiac β₁AR/β₂ARs were assessed through competitive binding of [³H]CGP-12177 with specific β₁AR or β₂AR blockers. G_αs and G_αi proteins were assessed by Western blot and cAMP accumulation by ELISA. Echocardiograms were recorded in anesthetized birds to evaluate diastolic/systolic diameter and heart rate and tissue sections were stained for collagen. We found an increase in relative heart mass, β₁ARs and G_αs in prenatally hypoxic hearts. cAMP levels after isoproterenol stimulation and collagen content was not changed in H compared to N but in vivo echocardiograms showed systolic contractile dysfunction. The changes in βAR and G-protein subtypes may be indicative of an early compensatory stage in the progression of cardiac dysfunction, further supported by the cardiac hypertrophy and systolic contractile dysfunction. We suggest that it is not the changes in the proximal part of the βAR system that causes the decreased cardiac contractility, but Ca²⁺ handling mechanisms further downstream in the βAR signaling cascade.