1020: The consequences of balloon induction on the risk for concomitant preterm birth

The prevalence of elective inductions is anticipated to increase in the years to come due to growing body of evidence demonstrating improved birth outcomes. Nevertheless, concerns have been raised regarding mechanical iatrogenic disruption of the cervical stroma due to induction of labor, with possible increased risk for preterm birth. Therefore, the aim of this study is to evaluate subsequent pregnancy outcomes following balloon induction. A retrospective case control study including all women who underwent induction of labor at a single tertiary care center, between December 2011 to August 2018. Study group included women after elective balloon induction (n=737) were compared to women induced by slow release vaginal PGE2 (Propess) (n=112). Inclusion criteria included: ≥37 weeks of gestation, concomitant spontaneous labor and singleton pregnancy. Women after cesarean delivery and multiple gestational pregnancy were excluded. Demographics, obstetrical characteristics and pregnancy outcomes were compered between groups. Data were analyzed using non-parametric tests. Age, gravidity and parity were comparable between the groups. No differences were observed in the concomitant gestational age at birth [40.3 (39.1-40.4) vs. 39.3 (38.1-40.5), balloon and slow release vaginal PGE2 respectively; p=0.12]. Furthermore, delta between concomitant to previous delivery week was comparable between groups (p=0.73). Normal vaginal delivery was reported in 91.9% (n=679) and in 93.8% (n=105) of the balloon and slow release vaginal PGE2 groups, respectively (p=0.49). Cervical dynamics was not seen in any of the patients in both groups. Balloon induction of labor was not associated with earlier gestation in concomitant delivery.