Occipito-Frontal Diameter (OFD)

Data sources

• INTERGROWTH-21st: Centile and z-score tables for OFD.
• NICHD: Does not include OFD as a standard measurement.

Mapping strategy

• OFD is often used in combination with BPD to compute head circumference.
• Not typically interpreted in isolation, but values <3rd or >97th centile may flag abnormal skull shape.

Planned extensions

• Add derived indices (e.g., cephalic index = BPD / OFD x 100).