Competing interests: The BMJ has judged that there are no disqualifying financial ties to commercial companies. The authors declare the following other interests: JS is a member of WHO Strategic and Technical Advisory Group of Experts (STAGE) for maternal, newborn, child, adolescent health and nutrition, RCOG Centre for Quality Improvement and Clinical Audit strategic advisory forum, and the expert group on Enabling Safe, Quality Midwifery Services and Care in Northern Ireland. JC was an unpaid expert witness for House of Lord’s Committee on Preterm Birth. Further details of The BMJ policy on financial interests are here: https://www.bmj.com/sites/default/files/attachments/resources/2016/03/16-current-bmj-education-coi-form.pdf