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. Author manuscript; available in PMC: 2010 Nov 1.
Published in final edited form as: Ultrasound Obstet Gynecol. 2009 Nov;34(5):556–565. doi: 10.1002/uog.7327

Table 1.

Fetal Weight Estimation - Original and modified Hadlock Models

Model Original and Modified Weight Estimation Functions N R2 MSE Mean %
Difference		 SD %
Difference
OH1 Original Hadlock Model (AC, FDL)
Log10BW = 1.3598 + 0.051 (AC) + 0.1844 (FDL) - 0.0037 (AC × FDL) 		256 -- -- 8.79 9.1
OH2 Original Hadlock Model (BPD, AC, FDL)
Log10BW = 1.4787 + 0.0458 (AC) + 0.158 (FDL) - 0.003343 (AC × FDL) + 0.001837 (BPD2) 		140 -- -- 7.69 8.5
MH1 Modified Hadlock Model (AC, FDL)
Log10BW = 1.2487 + 0.055 (AC) + 0.1987 (FDL) - 0.0043 (AC × FDL) 		256 0.98 0.129 0.35 8.3
MH2 Modified Hadlock Model (BPD, AC, FDL)
Log10BW = 1.4035 + 0.0441 (AC) + 0.177 (FDL) - 0.0037 (AC × FDL) + 0.0027 (BPD2) 		140 0.99 0.106 0.29 7.6

BPD = biparietal diameter; AC = abdominal circumference; AVol = fractional arm volume; TVol = fractional thigh volume; MSE = mean squared error

Original Hadlock models (OH1 and OH2) are expressed with their published R-square values (Hadlock FP, et al. Radiology 1984;150:535-40)

Modified Hadlock models (MH1 and MH2) are expressed with their adjusted R-square values.

Mean % difference = [(estimated weight - birth weight)/birth weight] × 100