Figure 2: ROC curves of the maternal pelvic inlet and outlet and the mode of the vaginal delivery. Spontaneous vaginal delivery was chosen as the reference result. (a) ROC curve for maternal inlet. The area under curve is 0.566 with the value of 0.18 and 95% confidence interval of 0.465–0.667. (b) ROC curve for maternal outlet. The area under curve is 0.573 with the value of 0.14 and 95% confidence interval of 0.484–0.622.