Simple Models to Predict Vaginal Delivery and Spontaneous Fetal Occiput Rotation Based on Intrapartum Ultrasound and Maternal Characteristics

Abstract

It is important to monitor labor progress and identify the possibility of vaginal birth. Based on intrapartum sonographic findings, we describe the prediction models for evaluating fetal occiput rotation and vaginal delivery. We performed serial intrapartum ultrasonography in nulliparous women with singleton cephalic presentation at term in the latent phase and every three hours after that. Six hundred and fourteen women were included in our study, of whom 524 underwent vaginal delivery, and 90 required cesarean section. The percentage of women with fetuses in non-occiput anterior(non-OA) position at the latent phase was 53.9% (331 cases), as 257(77.6%) women underwent spontaneous rotation to OA position before delivery, 74 (22.4%) women were with persistent occiput posterior (OP) position or occiput transverse (OT) position. We developed a model based on the maternal height and middle angle to predict the spontaneous fetal occiput rotation, with the C statistic was 0.667 (95%CI 0.583-0.751). Moreover, a prediction model based on the maternal height and angle of progression to evaluate whether women underwent vaginal delivery was also developed, of which the C statistic was 0.738(95% CI: 0.763-0.793). Both models showed satisfactory calibration. Our approach provides helpful information for predicting vaginal delivery and internal fetal occiput rotation.