Factors affecting rotation of occiput posterior position during the first stage of labor.

Introduction: Fetal occiput posterior (OP) positions account for 15 to 20% of cephalic presentations and are associated with poorer maternal and neonatal outcomes than occiput anterior (OA) positions. The aim of this study was to identify maternal, neonatal and obstetric factors associated with rotation from OP to OA position during the first stage of labor.
Material and Methods: This secondary analysis of a multicenter randomized controlled trial (EVADELA) included 285 laboring women with ruptured membranes and a term fetus in OP position. After excluding women with cesarean deliveries before full dilatation, we compared two groups according to fetal head position at the end of the first stage of labor: those with and without rotation from OP to OA position. Factors associated with rotation were assessed with univariate and multivariate analyses using multilevel logistic regression models.
Results: The rate of anterior rotation during the first stage was 49.1%. Rotation of the fetal head was negatively associated with excessive gestational weight gain (adjusted odds ratio [aOR]: 0.37, 95% confidence interval [CI]: 0.17-0.80), macrosomia (aOR: 0.35, 95% CI: 0.14-0.90), direct OP position (aOR: 0.24, 95% CI: 0.09-0.65), and prelabor rupture of membranes (aOR: 0.40, 95% CI: 0.19-0.86). Oxytocin administration was the only factor positively associated with fetal head rotation (aOR: 2.17, 95% CI: 1.20-3.91).
Discussion: Oxytocin administration may affect rotation of OP positions during the first stage of labor. Further studies should be performed to assess the risks and benefits of its utilization for managing labor with a fetus in OP position.
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