Main Findings
In the present study, we performed intrapartum ultrasonographic assessments of fetal head station and position, which differed significantly at various times during the labor. We developed a binary logistic regression model based on maternal height and angle of progression to predict 73.8% of vaginal deliveries at the latent labor phase. Moreover, a simple prediction model combining middle angel and maternal height for estimating the spontaneous fetal head rotation was also obtained. Because these two models both require only two parameters (one clinical variable and one intrapartum ultrasound parameter) that can be easily acquired, we suppose both models can be applied in any delivery unit.