Agreement between early ultrasound dating versus gestational age (GA) determined by last menstrual period (LMP), Ballard Score and AMANHI machine learning models (A, B, C, D)
| GA determined by: | N | Mean difference in days (95% CI) (GA test method—GA ultrasound) | Bland-Altman 95% limits of agreement (in days) | Precision of predicted GA (in days)* |
| LMP† (<37 weeks) | 7428 | −1.69 (−2.15 to –1.24) | (−41.0 to 37.6) | ±39.3 |
| Original Ballard Score‡ | 7428 | 9.16 (8.87 to 9.44) | (−15.3 to 33.6) | ±24.5 |
| AMANHI model A Newborn 10-characteristics § (including birth weight) | 7428 | 0.03 (−0.17 to 0.23) | (−17.3 to 17.4) | ±17.3 |
| AMANHI model B Newborn 10-characteristics§+LMP† | 7428 | 0.03 (−0.15 to 0.22) | (−15.7 to 15.8) | ±15.7 |
| AMANHI model C Birth weight+LMP† | 7428 | 0.07 (−0.13 to 0.26) | (−16.6 to 16.8) | ±16.7 |
| AMANHI model D Birth weight+head circumference | 7428 | 0.06 (−0.15 to 0.28) | (−18.3 to 18.4) | ±18.4 |
*Interpretation: Refers to the precision of the predicted GA values estimated by the test method bias (95% CI of the individual differences) around the mean difference.
†LMP: In this study LMP was collected from maternal recall at <20 weeks gestation in all sites as part of prospective research studies.
‡Ballard Score: GA was calculated from the Ballard signs as described in Ballard et al29 using the formula GA=((2×score)+120))/5.
§AMANHI 10-characteristics: Birth weight, head circumference, chest circumference, foot length, breast bud diameter, breast development, foot surface (plantar creases), skin texture, ankle dorsiflexion, infant sex.
AMANHI, Alliance for Maternal and Newborn Health Improvement.