Direct measurements of cardiac function and the impact of hypoxic incubation in late stage fetal chickens have not been previously quantified, while systemic effects have been extensively documented. Given reported cardiac enlargement in hypoxic incubated fetal chickens, we sought to investigate potential changes in cardiac function that may accompany this phenotype.METHODSWhite leghorn fetal chickens were incubated at 21% (N) or 15% oxygen (H) for 19 days. Anesthetized animals from both groups had left ventricular (LV) output measured with a Transonic flow probe, or had a 3.5mm Scisense ADVantage catheter inserted to measure LV pressure‐volume relationships at 21% and 10% O2 during aortic occlusions. RNA expression was measured by quantitative PCR. Data are presented as mean±SEM.RESULTSHeart weight proportionate to body weight was higher in the H group (6.6±0.3 vs. 5.6±0.2, p<0.05). At 21% O2, stroke volume was lower in the H than the N group (16±2μl vs. 32±4, p<0.05). Pressure‐volume characteristics were similar between groups. Key genes in cardiac growth pathways were upregulated by hypoxic incubation (cyclin D1 160% of N, p21 240%, Notch1 200%, p<0.05), as was expression of collagens 1α2 and 3α1 (229% and 213%, p<0.05).CONCLUSIONIntracardiac pressure‐volume parameters can be measured in chick fetuses at day 19 of incubation. Hypoxic incubation changes cardiac function and activates growth and differentiation pathways. The results reflect adaption to hypoxia in the fetus, the long‐term consequences of which are uncertain.Supported by funding from NSF IOS‐0845741, NIH K12HD043488 & NIH 1R011HD071068.