Prenatal Ultrasound Frames acquired by novice operators using a pre-specified blind-sweep protocol. Annotations of fetal abdominal circumference in frames where it could be measured. Reference abdominal circumference measurements (in mm) per sweep. A detailed description of the imaging data and annotations can be found here. Update notes: Version 1.1 includes updated circumference measurements. In version 1.0, these measurements were incorrectly computed and were too large by a factor of 2, as the minor and major axes were used instead of the semi-minor and semi-major axes.