The objective of the study was to measure fetal aortic pulse wave velocity and lumen diameter waveforms and subsequently calculate local distensibility, compliance and pulse pressure. A dedicated algorithm for optimizing lumen diameter assessment from radiofrequency ultrasound data is described. Biplane raw data were obtained from a matrix array transducer. We evaluated 83 confirmed, normally developing pregnancies at 22-38 wk. Fetal aortic pulse wave velocity (PWV, m/s) = 0.047 x gestational age (wk) + 1.241, and the distensibility coefficient (1/kPa) = 1/(1.04 x PWV(2)). The logarithm of the local compliance index (mm(2)/kPa) and the pulse pressure (kPa) were both linearly related to gestational age as 0.022 x GA (wk) - 0.343 and 0.012 x GA (wk) + 0.931, respectively. In conclusion, fetal aortic elastic properties can be derived from phase-sensitive radiofrequency data and multiline diameter assessment. Future studies may shed further light on the developmental origins of vascular health and disease.