May the indication for a previous cesarean section affect the outcome at trial of labor in women with induction of labor? A retrospective cohort study.

Introduction: Cesarean sections are increasing worldwide and are associated with altered risks of complications for both mother and child. Vaginal birth after cesarean section is associated with lower maternal and neonatal morbidity than in repeat cesarean section. Only a few studies have considered the indication for the previous cesarean section to be of importance for the outcome of subsequent labor. The aim of this study was to evaluate whether the indication for a previous cesarean section affects the outcomes at a subsequent delivery in women with induction of labor.

Material and methods: This retrospective cohort study of the four largest delivery units in Stockholm during 2012-2015 included 1150 women with one previous cesarean section with induction of labor.

Inclusion criteria: women with induced labor and a previous cesarean section, singleton pregnancy, cephalic presentation, gestational age of ≥34 weeks. The women were grouped by indication for the previous cesarean section.

Primary outcome: mode of delivery (vaginal birth after previous cesarean section or repeat cesarean section).

Secondary outcomes: induction to delivery time, postpartum hemorrhage, uterine rupture. Neonatal outcomes: birth weight, Apgar score <7, arterial umbilical cord blood gas pH <7.0.

Results: Our study found that the indication of labor dystocia at the previous cesarean section, increased the risk of repeat cesarean section (aOR 5.35; 95% CI: 1.64-17.50) in women with induction of labor. Other risk factors for repeat cesarean section were birth weight >4000 g, maternal BMI ≥30 or if vaginal prostaglandin was used as the method for induction of labor. A previous vaginal delivery and use of oxytocin increased the chance of a vaginal delivery in this group of women.

Conclusions: Our study showed that the indication for the previous cesarean section affects the outcome in the subsequent delivery in women with induction of labor. If the indication for the previous cesarean section was labor dystocia, the risk of repeat cesarean section was increased.