Influence of maternal factors and mode of induction on labour outcomes: a pragmatic retrospective cohort study

Abstract

Since recent research indicates that other modalities are at a minimum non-inferior to the NICE-recommended hormonal agent prostaglandin E2 (PGE2), a retrospective cohort study was conducted on 1971 consecutively induced singleton pregnancies. Multinominal regression analysis showed that the odds ratio (OR) for vaginal delivery with balloon-mediated labour induction (84% vaginal deliveries; OR 1.6; 95% CI 0.7–3.5) is similar to the PGE2 agents propess (81%; OR 1.2; 95% CI 0.68–1.98) and prostin (79%; OR 0.99; 95% CI 0.55–1.79) when using a triple multi-agent induction as a reference. On the other hand, combining the propess and prostin (60% vaginal deliveries; OR 0.45; 95% CI 0.21–0.96) and attempting quadruple combinations of the induction modalities (56%; OR 0.37; 95% CI 0.16–0.85) yields significantly poorer outcomes. However, compared to the known factors associated with increased caesarean section rates, such as an increased maternal age, nulliparous pregnancies and a history of caesarean section, the differential impact of different induction modalities appear less pronounced.Impact statementWhat is already known on this subject? Recent published data from controlled clinical trials have shown that other labour-inducing agents, including balloon catheters, are as effective as prostaglandin E2 (PGE2) in achieving a vaginal delivery.What do the results of this study add? The data from this pragmatic retrospective cohort study supports the findings of others that the use of a balloon is as effective as PGE2. It also demonstrates that regular clinical practice can differ from an experimental environment, with patients receiving multiple induction modalities in a daily practice. Both the combination of different PGE2 medications and a quadruple labour induction approach are associated with poorer results, as measured by the vaginal delivery rate. The data presented here also confirms that a nulliparous status, a maternal age and a history of caesarean section are associated with reduced odds of achieving a vaginal delivery.What are the implications of these findings for clinical practice and/or further research? The body of evidence showing favourable results with a balloon induction is growing. Furthermore, there are limits to the effectiveness of combining the different induction modalities. Maternal and perinatal factors associated with a risk of caesarean section further complicate labour induction management.