This study was done on 50 pregnant females with current fetal intrauterine skeletal dysplasia between 15 and 30 weeks. Maternal serum alpha fetoprotein was withdrawn as a blood sample between 16 weeks and 18 weeks of gestational. 2D detailed obstetrics ultrasound was done between gestational ages 15 weeks and 30 weeks complemented by 3D US. The Ultrasonography examination was done at the prenatal diagnosis unit in the National Research Centre.It was found that high resolution 2D ultrasound provided us with high degree of accuracy in the diagnosis of fetal skeletal dysplasia which was complemented with 3D ultrasound which provides a lower accuracy in diagnosis.Post Natal Diagnosis of the fetuses showed how was 2D (BackBone) and 3D helped the diagnosis and counseling In addition, we found that we can use femur length to abdominal circumference ratio as new predictors for the lethality of fetal skeletal dysplasia.