Legends
Figure 1. Sonographic parameters of fetal head descent and rotation: (a) The angle of progression (AoP) in the transperineal longitudinal plane; (b) The head-perineum distance (HPD) measured on a sagittal scan and (c) the midline angle in the transperineal axial plane.
Figure 2. Receiver operating characteristic curve for the prediction model of the midline angle combined with the maternal height. The area under the curve (AUC) for the prediction of successful fetal head rotation was 0.667 (95% CI, 0.583-0.751; P<0.001).
Figure 3. Calibration curves for prediction models. (a) Model of fetal occiput rotation; (b) Model of vaginal delivery.
Figure 4. Receiver operating characteristic curve of the combination of maternal height and angle of progression (AoP) for predicting vaginal delivery at different scan intervals. The first scan time (T1) was at the latent labor phase (red line). Subsequent scans were performed at 3 hours intervals (T2, blue line; T3, green line). The areas under the curves (AUCs) for the prediction model were 0.738 (95% CI, 0.763-0.793; P<0.001) at T1, 0.820 (95% CI, 0.752-0.888; P<0.001) at T2 and 0.940 (95% CI, 0.885-0.995; P<0.001) at T3, respectively.
Table 1 Maternal and newborn characteristics of participants
Table 2 The angle of progression (AoP), head–perineum distance (HPD) and midline angle (MLA) at different time points, according to the mode of delivery
Table 3 Final logistic regression models to predict spontaneous fetal occiput rotation and vaginal delivery