Journal of Ultrasound in Medicine, Vol 15, Issue 10 669-672, Copyright © 1996 by American Institute of Ultrasound in Medicine
New formula for estimating fetal weight below 1000 g: comparison with existing formulas
F. Scott, P. Beeby, J. Abbott, D. Edelman and A. Boogert
Department of Perinatal Medicine, King George V Hospital, sydney, Australia.
Most estimated fetal weight formulas have been derived and tested with
larger fetuses, yet accuracy in predicting birth weight is more critical at
the limit of viability. Complete data from 142 pregnancies in which
delivery took place within 7 days of an ultrasonographic examination were
used to create an appropriate formula for fetuses less than 1000 g and
compare it with 10 currently available formulas. Our formula (In [BW] =
0.66 x 1n [HC] + 1.04 x 1n [AC] + 0.985 x 1n [FL]) was significantly more
accurate than all other formulas and also performed better on a prospective
cohort of 27 fetuses with estimated fetal weight less than 1000 g. Of the
existing formulas, the Hadlock formula (using head circumference, abdominal
circumference, femur length) was the most accurate, being significantly
more accurate than all but the Woo formula with all but the Woo formula.
