Journal of Gynecological Research and Obstetrics 021 system, five-dimensional 5D Long Bone (5D LB) was introduced with an automated system that allow the volume measurement to be completed in just a few seconds and eliminate operators variability which makes it more useful in clinical practice [8]. Also the fact that ethnic and racial variation exists in fetal biometry [2], mandate testing the hypothesis that 5D or 3D ultrasonography measurement of fetal thigh volume may be more accurate in prediction of fetal weight in comparison to the conventional two dimensional Hadlock formula in this study population Patients and Methods This study is a prospective study conducted at Ain Shams University Maternity Hospital, a tertiary care center in Cairo which receives around a hundred and fifty pregnant patients daily in the outpatient and the emergency departments and has a specialized fetal medicine unit. The study protocol was in agreement to the Helsinki Declaration of Ethical Medical Research [updated in South Korea, 2008]. Acceptance of local institutional committee and the ethical committee of the faculty of medicine was obtained before commencing the trial and all participating women signed a written informed consent after proper explanation. To overcome these defects, long bone automated detection