Table 5.

Agreement and reliability of fetal biometrics z scores using Intergrowth 21st and Salomon equations in the third trimester

Anthropometrics	Mean ± SD	p-value*	Median (IQR)	p-value†	Range
Biparietal diameter
Intergrowth 21	−0.91 ± 0.70		−0.89 (−1.31; −0.44)		−2.62; 0.78
Salomon	− 0.53 ± 0.64		−0.49 (− 0.90; − 0.11)		−2.10; 1.00
Difference	−0.39 ± 0.07	<  0.001	−0.38 (− 0.44; − 0.34)	<  0.001	−0.53; − 0.22
LOA	−0.52; − 0.25
ICC	0.85
Abdominal circumference
Intergrowth 21	0.81 ± 0.71		0.75 (0.29; 1.21)		−0.95; 2.89
Salomon	0.35 ± 0.43		0.36 (0.02; 0.63)		−0.68; 1.45
Difference	0.45 ± 0.31	<  0.001	0.37 (0.25; 0.64)	<  0.001	−0.27; 1.48
LOA	−0.16; 1.07
ICC	0.66
Head circumference
Intergrowth 21	0.76 ± 0.70		0.70 (0.39; 1.21)		−0.87; 2.49
Salomon	0.85 ± 0.48		0.79 (0.58; 1.17)		−0.28; 2.05
Difference	−0.09 ± 0.22	<  0.001	− 0.09 (− 0.18; 0.07)	0.001	−0.59; 0.44
LOA	−0.52; 0.35
ICC	0.92
Femur length
Intergrowth 21	1.09 ± 1.15		1.15 (0.53; 1.75)		−2.44; 3.55
Salomon	0.07 ± 0.90		0.13 (−0.38; 0.55)		− 2.54; 2.02
Difference	1.02 ± 0.26	<  0.001	1.04 (0.91; 1.16)	<  0.001	0.10; 1.53
LOA	0.50; 1.53
ICC	0.65

* Paired t test p value

† Wilcoxon signed ranks test p value

LOA limits of agreement, ICC intraclass correlation coefficient