Fetal Weight Calculator (Hadlock 4-Parameter)
Estimate fetal weight from biparietal diameter, head circumference, abdominal circumference and femur length using the Hadlock-4 regression.
How to Use the Fetal Weight Calculator (Hadlock 4-Parameter)
- Enter BPD in cm.
- Enter head circumference in cm.
- Enter abdominal circumference in cm.
- Enter femur length in cm.
- Click Calculate.
Casi d'Uso
- •Antenatal growth monitoring.
- •Macrosomia screening.
- •Training in obstetric ultrasound.
Formula
log₁₀(EFW) = 1.3596 − 0.00386·AC·FL + 0.0064·HC + 0.00061·BPD·AC + 0.0424·AC + 0.174·FL.
Domande Frequenti
How accurate is Hadlock-4?
Within roughly ±10–15% of actual birth weight when measurements are taken correctly. Error rises above 4 kg and with maternal obesity.
Which Hadlock formula is this?
The 4-parameter BPD+HC+AC+FL variant, generally considered the most accurate of the Hadlock family.
Medical disclaimer
Educational only. Not a substitute for obstetric clinical judgment — ultrasound-based EFW must be interpreted by a trained clinician.