Hi Niadla
Below is an extract from their own policy. I hope you find it useful

Australasian Society for Ultrasound in Medicine
Policies and Statements
D7
Statement On Normal Ultrasonic Fetal Measurements
June 1991, Reaffirmed May 1996, Revised May 2001
FETAL WEIGHT
No formula for estimating fetal weight has achieved an accuracy which enables us to recommend its
use. It should be noted that errors are reported for one standard deviation only and that even at this
level the accuracy is disappointing.