Methods for induction of labour
Authors:   , de Vaan Maria Dimphena Theodora 
Published: November 2023

The aim of this thesis was to further investigate obstetrical and perinatal safety outcomes of induction of labour with a balloon catheter in comparison to other induction agents in a general pregnant population as well as in specific subgroups of people.

Chapter 1 introduces a global overview of what is known on different methods for induction of labour.

In Chapter 2, we describe a systematic review and meta-analyses on the safety and of mechanical labour induction in comparison to different pharmacological methods. We included a total of 112 randomised controlled trials, with 104 studies contributing data involving 22,055 individuals. We concluded that a balloon is as effective as vaginal PGE2, but a balloon seems to have a more favourable safety profile. And with the evidence at hand, more research on this comparison does not seem warranted. And although a balloon catheter may be slightly less effective compared to oral misoprostol, it remains unclear if there is a difference in safety outcomes for the neonate as the results were still too imprecise to make a valid judgement.

Chapter 3 describes the result of a secondary analysis of a combined database of two previously published randomised controlled trials (the PROBAAT-1 and PROBAAT-2 trial) about the safety aspects of a 30cc-Foley balloon catheter, vaginal PGE2 and oral misoprostol in pregnancies with small-for-gestational-age neonates (n=425). Our primary outcome was a composed adverse neonatal outcome of Apgar score <7 after 5 minutes and/or a pH in the umbilical artery <7.05 and/or NICU admission. We concluded that in pregnancies with a small-for-gestational-age neonate, a Foley catheter is probably a safer induction method compared to oral misoprostol. For PGE2, the numbers were too low to make a valid judgement compared to a Foley balloon catheter within this specific subgroup.

In Chapter 4 we describe the results of another secondary analysis we performed on the PROBAAT-1 and PROBAAT-2 trials, on the effect of labour induction with a Foley balloon catheter, oral misoprostol or vaginal PGE2 in patients with obesity (BMI ≥30). Our primary outcomes were caesarean section and post-partum-haemorrhage (PPH) (n=517). We concluded that a Foley balloon catheter might be equally safe and effective in obese persons although and there might be an increased risk of a failed placement of the Foley balloon catheter in this specific subgroup.

In Chapter 5 we explored the possible risk of preterm birth in a subsequent pregnancy after term induction with a Foley balloon catheter. For this purpose, we conducted a follow-up study of the PROBAAT-1 and PROBAAT-2 studies, in which patients were randomised to either a 30cc Foley catheter or prostaglandins (Prostaglandin E2; PROBAAT 1 or oral misoprostol; PROBAAT 2).
Results of this studies study show that induction of labour with Foley catheter was not associated with an increased risk of preterm birth in a subsequent pregnancy.

In Chapter 6 we discuss our findings in broader perspective in and in relation to what is already known in existing literature. From within this context, we made recommendations for practice and future research