Fetal dosimetry studies require the development of accurate 3D models of the fetus. This paper proposes a 3D articulated fetal growth model including skeleton, body envelope, brain and lungs based on medical images of ten different fetuses acquired in clinical routine. The structures of interest were semi-manually segmented from the images and surface meshes were generated. A generic mesh of each structure has been deformed towards the segmented ones. By interpolating linearly between the subjects of the database, each structure can be estimated at any age and in any position. This process results in an automated model, the operator being only required to specify the age and position of the desired estimated fetus.