Table 2.

Prediction properties of internal validation

Method	Internal Validation
	AUC	Cutoff	Sensitivity	Specificity	PPV	NPV
Logistic Regression*	0.949	0.43	0.83	0.96	0.85	0.94
Total score	0.867	19	0.80	0.82	0.57	0.93

^*Based on the combination of uterine peristalsis (Uterine peristaltic wave frequency, UPF), uterine spiral artery (Uterine spiral artery resistant index, RI), ultrasound elastography (Ultrasound elastography strain radio, SR) and age.