| AUC | Area under the curve |
| BMI | Body mass index |
| CL | Cervical length |
| ICC | Intraclass correlation coefficient |
| ISUOG | International Society of Ultrasound in Obstetrics and Gynecology |
| TAUS | Transabdominal ultrasound |
| TPUS | Transperineal ultrasound |
| TVUS | Transvaginal ultrasound |
| UCA | Uterocervical angle |