Optimising the outcomes of induction of labour through robust evidence. 2. Different methods of induction of labour: an individual participant data network meta-analysis of randomised controlled trials.

Induction of labour is carried out when the risks of advancing gestation outweigh maternal and foetal benefits. It is one of the most frequent obstetric interventions, accounting for nearly one-fourth of all births in high-income countries and generally lower rates in low- and middle-income countries. Recent rates of labour induction have been reported to be as high as 34% in the UK, 23% in the USA, and 25-35% in Australia. This rate will likely rise further due to evidence from the recent ARRIVE trial. The body of evidence is still growing. The goal is to find a method that can mimic the natural, spontaneous onset of labour with equal or higher maternal satisfaction and prioritise the seemingly less-medicated methods, putting safety first. There should be more room for client satisfaction, specifically evaluated in qualitative studies. Attention should also be given to the practical, cost-effective methods in low- and middle-income countries as they bear a significant portion of the global maternal and perinatal morbidity and mortality. At present, the current clinical guidelines recommend only three primary methods for cervical ripening: vaginal dinoprostone, mechanical (balloon catheter and osmotic dilator) and oral misoprostol. Our recent IPD meta-analysis suggests that low-dose vaginal misoprostol can be a useful addition to contemporary obstetric practice (https://pubmed.ncbi.nlm.nih.gov/38425020/). Another IPD meta-analysis from our team, a large IPD meta-analysis on balloon versus vaginal prostaglandins, recently showed that balloon catheters had favourable perinatal safety and comparable maternal safety and mode of delivery (https://pubmed.ncbi.nlm.nih.gov/36366885/). We have also shown that oral misoprostol is more effective than balloon catheters with comparable maternal outcomes but potentially worse perinatal safety (https://pubmed.ncbi.nlm.nih.gov/33258514/). Further, an IPD meta-analysis comparing single-balloon versus double-balloon on IOL has shown comparable vaginal birth rates and maternal and perinatal outcomes (https://pubmed.ncbi.nlm.nih.gov/37417714/). These projects help expand the range of available methods and allow for a greater degree of personalisation. A large network meta-analysis using IPD would be the best possible solution to summarise and draw wider and more practical implications into clinical practice for all these comparisons under one study.