Persistent occiput posterior position: predictive factors of spontaneous rotation of the fetal head.

Objectives: To assess factors associated with spontaneous rotation in the occiput anterior position for fetuses in persistent occiput posterior (OP) during the second stage of labor. To evaluate maternal and fetal outcomes after spontaneous rotation of persistent OP.

Methods: This is a prospective cohort of 495 women with fetuses in persistent OP position, confirmed with ultrasonography during the second stage of labor. We performed simple logistic regressions, followed by multiple logistic regressions.

Results: Among 495 women with fetuses in persistent OP position, 78 fetuses (16%) underwent a spontaneous rotation during the second stage of labor. The multivariate analysis found that a short duration of the first stage of labor (<7 h) was associated with a spontaneous rotation of the fetal head in the second stage of labor (OR 0.43 [0.23; 0.76. There were fewer episiotomies (25.6% vs 52.3%,  < .01), cesarean sections (0% v. 5.4%,  = .03), and instrumental deliveries (8.9% vs. 50%,  < .01) in the "spontaneous rotation" group, and the two groups were similar regarding post-partum hemorrhage.The newborns in the "spontaneous rotation" group had a higher Apgar score at 1 min (10 v. 9,  = .02). The two groups did not differ for other neonatal parameters, such as arterial pH value, Apgar score at 5 min, birth trauma, or transfer into the pediatric unit.

Conclusion: A shorter duration of the first stage of labor (< 7 h) is a predictive factor of spontaneous rotation in the occiput anterior position for fetuses in persistent OP position. A spontaneous rotation in case of an OP position is associated with better maternal and fetal outcomes.