Objective: To evaluate the effect of fetal position on 1) second-stage labor duration and 2) indicators of maternal and neonatal morbidity.
Methods: A retrospective cohort study was conducted using a database from a previously reported randomized clinical trial. The data set includes 210 women with the fetus in a posterior position, 200 women with the fetus in a transverse position, and 1,198 women with the fetus in an anterior position. Mean durations of the second stage of labor for different fetal positions were compared using Tukey studentized test. A multivariate logistic regression model was performed to examine the determinants of prolonged second-stage duration (>or= 3 hours). Kaplan-Meier survival curves were used to graph and compare the duration of the second stage of labor for spontaneous delivery according to the fetal position at full dilatation and study group.
Results: Fetal malposition at full dilatation was associated with a significantly increased risk of instrumental vaginal delivery, cesarean delivery, oxytocin administration before full cervical dilatation, episiotomy, severe perineal laceration, and maternal blood loss of more than 500 mL (all P values < .01). Compared with the occiput anterior positions, there were significant differences in the duration of the second stage of labor, with a mean of 3.1 hours (95% confidence interval [CI] 3.0-3.2) for occiput anterior positions, 3.6 hours (95% CI 3.3-3.9) for occiput transverse positions (P < .05), and 3.8 hours (95% CI 3.5-4.1) for occiput posterior positions (P < .05) in the delayed pushing group. For the early pushing group, means were 2.2 hours (95% CI 2.1-2.3) for occiput anterior positions, 2.5 hours (95% CI 2.3-2.8) for occiput transverse positions (P < .05), and 3.0 hours (95% CI 2.7-3.3) for occiput posterior positions (P < .05).
Conclusion: Fetal malposition at full dilatation results in a higher risk of prolonged second stage of labor and increases maternal morbidity indicators.
Level of evidence: II-2.