Search methods for identification of studies
The review was undertaken by searching the Ovid SP version of MEDLINE and EMBASE and the Cochrane Pregnancy and Childbirth Group’s Trials Register from 2011 to June 2019, followed by a manual search of references of relevant articles (reviews) and clinical guidelines (ACOG, NICE, UpToDate) for eligible studies. The length of the review period was restricted to 2011 to June 2019 because NICE clinical guideline for planned CS was updated in 2011 and scoping work showed that this guideline would enable identification of all relevant studies to capture the most important outcomes up until that date. The search strategy used in electronic databases was based upon a combination of terms relating to caesarean section; vaginal birth; and planned (Appendix S1). Abstracts and conference proceedings were excluded because of the high probability of incomplete data. Citations were collated using EndNote X9 and Microsoft Excel and duplicates were removed.