Table 4 Prediction equations for body weight (in g) from measured variables (in mm)

From crown-rump length (CRL):

BW = -0.696 + 0.0890(CRL)

R² = 0.938

From biparietal diameter (BPD):

BW = -34.08 + 32.10(BPD) - 11.130(BPD)² + 1.68(BPD)³-0.093(BPD)⁴

R² = 0.945

From abdominal circumference (AC):

BW = 4.20 - 0.76(AC) + 0.045(AC)² - 0.00078(AC)³

R² = 0.957

From crown-rump length (CRL) and abdominal circumference (AC):

BW = -0.757 + 0.0453(CRL) + 0.0334(AC)

R² = 0.962