Labor dystocia and oxytocin augmentation before or after six centimeters cervical dilatation, in nulliparous women with spontaneous labor, in relation to mode of delivery

Background: The effects of diagnosing and treating labor dystocia with oxytocin-infusion at different cervical dilatations are not fully evaluated. Therefore, we aimed to examine whether cervical dilatation at diagnose of dystocia and initiation of oxytocin-infusion was associated with mode of birth, obstetric complications and women’s birthing experience. Method: A retrospective cohort study, performed in a low cesarean section setting, included 588 nulliparous term women with spontaneous onset of labor and dystocia requiring oxytocin augmentation. The study population was divided into three groups according to cervical dilatation at diagnose of dystocia and initiation of oxytocin-infusion (≤5 cm, 6-10 cm, fully dilated) with mode of birth as the primary outcome. Secondary outcomes were obstetrical and neonatal complications and women´s experience of childbirth. The risk of operative birth was assessed using binary logistic regression with suitable adjustments (maternal age, body mass index and risk assessment at admission to the labor ward). The 6-10cm group was set as reference. Results: : Cesarean section was performed in 12% in the ≤5 cm group, 6% in the 6-10 cm group and 0% in the fully dilated group (p<.001), with no differences in the instrumental birth rates (11-14%, p=.569). There was no increased risk for operative birth (cesarean and vacuum) in the ≤5 cm group compared to the 6-10 cm group, adjusted OR 1.28 (0.78-2.08). The fully dilated group had a decreased risk of operative birth (adjusted OR 0.48 95% CI 0.27-0.85). The rate of a negative birthing experience was high in all groups (28.5%, 19% and 18% ) and the risk was increased among women in the ≤5 cm group compared with the 6-10 cm group, adjusted OR 1.76 (95% CI 1.05-2.95). Conclusions: : Women with dystocia requiring oxytocin augmentation diagnosed in second stage of labor had an increased chance of spontaneous vaginal birth compared with women requiring oxytocin augmentation in the late first stage of labor. No differences were shown between early and late active phase of first stage of labor concerning operative birth. Although, women with dystocia requiring oxytocin augmentation at ≤5 cm cervical dilatation seemed to have an increased risk of a negative birth experience.