Table 1 Distribution of prematurity and postmaturity rates along selected methods and comparison with 7–20-week ultrasound-based estimates of gestational age at birth—excluding outliers of birth weight for gestational age
Reference 7–20-week ultrasound | 21-28 weeks ultrasound | 29+ weeks ultrasound | Capurro method | Last menstrual periodv (sure) | Last menstrual period (all) | Algorithm | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
all | excluding outliers | all | excluding outliers | all | excluding outliers | all | excluding outliers | all | excluding outliers | all | excluding outliers | excluding outliers | |
n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | |
Prematurity | 150 (13.2) | 139 (12.5) | 92 (14.8) | 87 (14.2) | 96 (13.6) | 92 (13.2) | 94 (9.8) | 91 (9.6) | 143 (16.9) | 111 (13.8) | 191 (17.7) | 143 (14.0) | 180 (12.5) |
Term | 972 (85.5) | 959 (86.2) | 513 (82.6) | 510 (83.2) | 585 (82.9) | 583 (83.4) | 850 (88.4) | 843 (88.6) | 625 (73.8) | 614 (76.5) | 780 (72.1) | 768 (75.2) | 1227 (85.3) |
Post-maturity | 15 (1.3) | 14 (1.3) | 16 (2.6) | 16 (2.6) | 25 (3.5) | 24 (3.4) | 17 (1.8) | 17 (1.8) | 79 (9.3) | 78 (9.7) | 111 (10.3) | 110 (10.8) | 31 (2.2) |
Total | 1137 | 1112 | 621 | 613 | 706 | 699 | 961 | 951 | 847 | 803 | 1082 | 1021 | 1438 |
Prematurity* | |||||||||||||
Chi-square | - | - | 0.77 | 0.85 | 0.06 | 0.11 | 5.86 | 4.44 | 5.28 | 0.719 | 8.52 | 1.05 | 0.27 |
P-value | - | - | NS | NS | NS | NS | <0.05 | <0.05 | <0.05 | NS | <0.01 | NS | NS |
Kappa | - | - | 0.76 | 0.75 | 0.63 | 0.63 | 0.63 | 0.65 | 0.55 | 0.60 | 0.52 | 0.56 | - |
Sensitivity | - | - | 0.85 | 0.84 | 0.78 | 0.77 | 0.61 | 0.63 | 0.73 | 0.71 | 0.71 | 0.71 | - |
Specificity | - | - | 0.96 | 0.96 | 0.94 | 0.94 | 0.97 | 0.97 | 0.91 | 0.94 | 0.90 | 0.94 | - |
PPV | - | - | 0.74 | 0.74 | 0.59 | 0.60 | 0.74 | 0.77 | 0.52 | 0.61 | 0.50 | 0.61 | - |
PNV | - | - | 0.98 | 0.98 | 0.97 | 0.97 | 0.95 | 0.95 | 0.96 | 0.96 | 0.96 | 0.96 | - |
Post-maturity** | |||||||||||||
Chi-square | - | - | 3.67 | 3.82 | 10.1 | 9.32 | 0.706 | 0.757 | 69.0 | 72.1 | 82.8 | 88.2 | 3.27 |
P-value | - | - | 0.055 | 0.051 | <0.01 | <0.01 | NS | NS | <0.01 | <0.01 | <0.01 | <0.01 | NS |
Kappa | - | - | 0.262 | 0.262 | 0.048 | 0.050 | −0.016 | −0.016 | 0.099 | 0.067 | 0.142 | 0.091 | - |
Sensitivity | - | - | 0.98 | 0.98 | 0.97 | 0.97 | 0.98 | 0.98 | 0.91 | 0.91 | 0.90 | 0.90 | - |
Specificity | - | - | 0.50 | 0.50 | 0.14 | 0.14 | 0.00 | 0.00 | 0.33 | 0.36 | 0.47 | 0.50 | - |
PPV | - | - | 1.00 | 0.99 | 0.99 | 0.99 | 0.99 | 0.99 | 0.99 | 0.99 | 0.99 | 0.99 | - |
NPV | - | - | 0.19 | 0.19 | 0.04 | 0.04 | 0.00 | 0.00 | 0.05 | 0.05 | 0.06 | 0.06 | - |