"Colour Velocity Imaging (CVI)" permits acquisition of ultrasound Doppler data for quantitative analysis. CVI can be used to study the fetal circulation. In a pilot study we attempted measuring umbilical venous flow. Data acquisition is simple and fast. In the current implementation, data is sent to a work-station and analysed off-line. There is significant "intra-observer-variability" that could be attributable to true physiological variation or measurement inaccuracies. Measurement of fetal umbilical volume flow by CVI is a new and simple technique. Before its clinical use assumptions about the vessel, flow, variability and normal values must be verified in the fetus.