Abstract.The clinical estimate of the foetal weight is probably one of the most difficult parameters to obtain in the prenatal control. Only very accurate foetal body measurements reflect the gestation age and the weight of the foetus. A model is presented that performs an automated foetal age and weight determination from ultrasound by means of biparietal diameter, femur lenght and abdominal circumference parameters. The model proposed in this paper exploits the data in the images in three general steps. The first step is image preprocessing, to highlight useful data in the image and suppress noise and unwanted data. The next step is image processing, which results in forming regions that can correspond to structures or structure parts. The last step is image understanding, where knowledge on the specific problem is injected.