Table 3.
Agreement and reliability of fetal biometrics z scores using Intergrowth 21st and Salomon equations in the second trimester
| Anthropometrics | Mean ± SD | p-value* | Median (IQR) | p-value† | Range |
|---|---|---|---|---|---|
| Biparietal diameter | |||||
| Intergrowth 21 | − 0.48 ± 0.72 | − 0.47 (− 0.98; − 0.04) | −3.40; 3.11 | ||
| Salomon | − 0.15 ± 0.63 | − 0.12 (− 0.60; 0.24) | −2.68; 2.81 | ||
| Difference | − 0.33 ± 0.21 | < 0.001 | − 0.40 (− 0.48; − 0.22) | < 0.001 | − 0.72; 0.33 |
| LOA | − 0.74; 0.07 | ||||
| ICC | 0.85 | ||||
| Abdominal circumference | |||||
| Intergrowth 21 | 1.05 ± 1.18 | 0.95 (0.35; 1.59) | −2.07; 9.90 | ||
| Salomon | 0.29 ± 0.63 | 0.23 (−0.03; 0.58) | −1.37; 5.22 | ||
| Difference | 0.77 ± 0.60 | < 0.001 | 0.69 (0.40; 1.01) | < 0.001 | − 0.70; 4.68 |
| LOA | − 0.40; 1.94 | ||||
| ICC‡ | 0.54 | ||||
| Head circumference | |||||
| Intergrowth 21 | 0.75 ± 0.81 | 0.72 (0.14; 1.29) | −1.56; 4.24 | ||
| Salomon | 0.72 ± 0.61 | 0.67 (0.31; 1.14) | −0.94; 3.36 | ||
| Difference | 0.03 ± 0.33 | 0.18 | −0.02 (− 0.22; 0.23) | 0.85 | −0.62; 1.01 |
| LOA | −0.62; 0.68 | ||||
| ICC | 0.89 | ||||
| Femur length | |||||
| Intergrowth 21 | 1.21 ± 0.92 | 1.34 (0.63; 1.81) | −1.53; 4.00 | ||
| Salomon | 0.36 ± 0.71 | 0.47 (−0.07; 0.77) | −1.85; 2.57 | ||
| Difference | 0.85 ± 0.21 | < 0.001 | 0.88 (0.73; 0.97) | < 0.001 | 0.21; 1.43 |
| LOA | 0.43; 1.27 | ||||
| ICC | 0.63 | ||||
* Paired t test p value
† Wilcoxon signed ranks test p value
‡ Intraclass correlation calculation for abdominal circumference z scores excluded one participant with extreme values (9.9 using Intergrowth equations and 5.22 using Salomon equations)
LOA limits of agreement, ICC intraclass correlation coefficient