An ultrasound imaging system for producing a spatially compounded image of a fetus comprising: an input for receiving a plurality of three dimensional ultrasound image frames of a volumetric region comprising the fetus, wherein each 3D ultrasound image frame is acquired at a different look direction with respect to the fetus by means of an ultrasound probe ; and an ultrasound image processor responsive to the plurality of 3D ultrasound image frames, said processor arranged to: store the acquired plurality of 3D ultrasound image frames and an articulated fetal model, wherein the articulated fetal model includes a common fetal structure and at least one joint-limb relationship, segment each 3D image frame based on the articulated fetal model, wherein the ultrasound image processor is further arranged to adapt the articulated fetal model applied to a 3D image frame from the plurality, when a variation of the common fetal structure compared to another 3D image frame of the plurality is detected, provide a plurality of 3D images of the volumetric region with an identified relative orientation of the fetus with respect to the look direction of the segmented image, and analyze, based on the articulated fetal model, an overall confidence value of the plurality of the 3D images, said image quality analyzer is further arranged to compare the overall confidence value with an image compounding threshold. an input for receiving a plurality of three dimensional ultrasound image frames of a volumetric region comprising the fetus, wherein each 3D ultrasound image frame is acquired at a different look direction with respect to the fetus by means of an ultrasound probe ; and an ultrasound image processor responsive to the plurality of 3D ultrasound image frames, said processor arranged to: store the acquired plurality of 3D ultrasound image frames and an articulated fetal model, wherein the articulated fetal model includes a common fetal structure and at least one joint-limb relationship, segment each 3D image frame based on the articulated fetal model, wherein the ultrasound image processor is further arranged to adapt the articulated fetal model applied to a 3D image frame from the plurality, when a variation of the common fetal structure compared to another 3D image frame of the plurality is detected, provide a plurality of 3D images of the volumetric region with an identified relative orientation of the fetus with respect to the look direction of the segmented image, and analyze, based on the articulated fetal model, an overall confidence value of the plurality of the 3D images, said image quality analyzer is further arranged to compare the overall confidence value with an image compounding threshold. store the acquired plurality of 3D ultrasound image frames and an articulated fetal model, wherein the articulated fetal model includes a common fetal structure and at least one joint-limb relationship, segment each 3D image frame based on the articulated fetal model, wherein the ultrasound image processor is further arranged to adapt the articulated fetal model applied to a 3D image frame from the plurality, when a variation of the common fetal structure compared to another 3D image frame of the plurality is detected, provide a plurality of 3D images of the volumetric region with an identified relative orientation of the fetus with respect to the look direction of the segmented image, and analyze, based on the articulated fetal model, an overall confidence value of the plurality of the 3D images, said image quality analyzer is further arranged to compare the overall confidence value with an image compounding threshold. <EOS>