Labour duration and timing of interventions in women planning vaginal birth after caesarean section.

OBJECTIVE understanding the labour characteristics of women attempting vaginal birth after caesarean (VBAC) may suggest how to improve intrapartum management and may enhance success rates. Promoting VBAC is a relevant factor in decreasing overall caesarean section (c-section) rates. However, the labour processes of women attempting VBAC are not well investigated. The aim of this paper is to compare multiparae planning a first VBAC (pVBAC) with primiparae and with multiparae planning a second vaginal birth, all starting to give birth vaginally, with regard to (a) perinatal characteristics, (b) the timing of intrapartal spontaneous rupture of membranes (SROM) and of interventions, and (c) labour duration, with respect to the first and second stages. SETTING cohort study of women planning vaginal birth in 47 obstetric units in Lower Saxony, Germany. PARTICIPANTS 1897 primiparae, 211 multiparae with one previous c-section and 1149 multiparae with one previous vaginal birth. MEASUREMENTS secondary analysis of data from an existing cohort study. Kaplan-Meier estimates, log rank test, Wilcoxon test and shared frailty Cox regression models including time-varying covariates were used to compare the timing of interventions and labour duration between the subsamples. Analyses were done with the statistics programme Stata 13. FINDINGS perinatal and labour characteristics of multiparae with pVBAC mainly resembled those of primiparae and differed from those of multiparae planning a second vaginal birth. However, compared to primiparae, multiparae with pVBAC received oxytocin less often (48.82 versus 56.95%, p=0.024) and gave birth vaginally significantly less often (69.19 versus 83.40%, p<0.001). The timing of intrapartal SROM (2.67 versus 3.42 hours, p=0.112) and of interventions (amniotomy: 5.50 versus 5.83 hours, p=0.198; oxytocin: 5.75 versus 6.00 hours, p=0.596; epidural: 4.00 versus 4.67 hours, p=0.416; opioids: 3.83 versus 3.78, p=0.851) was similar to that in primiparae although timings of all interventions but not of SROM differed significantly from that in multiparae with second vaginal birth (SROM: 2.67 versus 2.67 hours, p=0.481; amniotomy: 5.50 versus 3.93 hours, p<0.001; oxytocin: 5.75 versus 4.25 hours, p<0.001; epidural: 4.00 versus 3.50 hours, p=0.009; 3.83 versus. 2.75 hours, p=0.026). Overall and first-stage labour duration were comparable to primiparae (overall labour duration: 8.83 versus 8.57 hours, HR=0.998, 95% CI=0.830-1.201, p=0.987; first stage: 7.42 versus 7.00 hours, HR=0.916, 95% CI=0.774-1.083, p=0.303) but significantly longer than in other multiparae (overall labour duration: 8.83 versus 4.63 hours, HR=0.319, 95% CI=0.265-0.385, p<0.001; first stage: 7.42 versus 4.25 hours, HR=0.402, 95% CI=0.339-0.478, p<0.001). However, the second stage of labour was significantly shorter in multiparae with pVBAC than in primiparae (0.55 versus 0.77 hours, HR=1.341, 95% CI=1.049-1.714, p=0.019), but longer than in multiparae with second vaginal birth (0.55 versus 0.22 hours, HR=0.334, 95% CI=0.262-0.426, p<0.001). KEY CONCLUSION labour patterns of multiparous women planning a VBAC differ from those of primiparae and other multiparous women. Multiparae with pVBAC should be considered as a distinct group of parturients. IMPLICATION FOR PRACTICE expectations regarding labour progression for multiparae with first pVBAC should be similar to those for primiparae. However, the chance that the second stage of labour might be shorter than in primiparae is relevant and motivating information for pregnant women with a previous c-section in deciding the planned mode of birth.