Correlation between fetal head dimensions on ultrasound and labor outcomes

Abstract

Background: Prolonged labor is a risk factor for numerous maternal and fetal complications and is among the primary causes of operative vaginal delivery and emergency cesarean section. Predicting prolonged labor remains challenging. This study was conducted to determine the relationship between fetal head dimensions on ultrasound and the duration of labor as well as other outcomes in Vietnam. Materials and Methods: A cross-sectional descriptive study was conducted on 191 nulliparous women admitted for delivery at the Hue University of Medicine and Pharmacy Hospital from January 2024 to April 2025. Independent samples t-test or Mann–Whitney U test was used for comparison, Pearson correlation coefficient (r) and ROC curve were analyzed to identify cut-off points for predicting the risk of cesarean section due to a prolonged second stage of labor. Results: There were 34/191 cases of cesarean section during the second stage. Fetal head dimensions in the cesarean section group were significantly larger than those in the vaginal delivery group (p<0.001). There was a weak positive correlation between biparietal diameter, head circumference and the duration of the second stage (p<0.001). Biparietal diameter and head circumference were larger in cases of complex perineal tears. The Area Under the Curve for biparietal diameter and head circumference in predicting cesarean section due to prolonged second stage was 0.718 and 0.704, respectively. Conclusion: Ultrasound measurement of fetal head dimensions has prognostic value for adverse maternal labor outcomes.