Table 2.

Factors contributing to the accuracy of measuring fetal head circumference (N = 216)

Variables	N = 216	Mean simple error (mm)	p value*
Parity
Primigravida	148	− 6.5	0.123
Multigravida	68	− 9.4
Gestational age (weeks)
28–33+6	32	− 5	0.035
34–36+6	53	− 8.1
> 37	131	− 8.9
Diabetes in pregnancy
Present	15	− 13.0	0.407
Absent	201	− 8.03
Presentation
Vertex	201	− 8.40	0.507
Breech	15	− 8.00
Placental location
Anterior	70	− 9.3	0.040
Posterior	128	− 8.4
Fundal	18	− 4.2
Amniotic fluid index
8–25	160	− 7.4	0.056
5–8	43	− 8.4
< 5	12	− 12
HC > 95th centile
Present	13	− 14	0.825
Absent	203	− 8
Mode of delivery
Normal	105	− 9.4	0.031
Instrumental	3	− 13.5
Cesarean	108	− 7.1

*p value < 0.05 is considered significant