Table 2.

Regression formula used to generate ultrasound biometry charts and tables of biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), and estimated fetal weight (EFW)

BPD
Mean = − 24.624 + 3.739* GA - 0.0004972* GA3
SD = 1.994 + 0.053* GA
HC
Mean = − 94.476 + 14.273* GA - 0.0020276* GA3
SD = 8.182 + 0.121*GA
AC
Mean = − 78.497 + 11.708* GA - 0.0009802* GA3
SD = 2.059 + 0.461* GA
FL
Mean = − 32.653 + 3.499* GA - 0.0005433* GA3
SD = 1.975 + 0.028* GA
EFW
Mean = 0.0095699*GA**4.4937733
SD = 0.00265083*GA**3.287346

Abbreviation: GA gestational age, SD standard deviation