Competing interests: We have read and understood BMJ policy on declaration of interests and declare the following interests: SB is a self employed obstetric academic and expert. She has been remunerated for chairing National Institute for Health and Care Excellence and National Collaborating Centre for Women’s and Children’s Health committees, external reviews of serious incidents, service reviews, and occasional medicolegal advice (including as a member of MDU case committee and council), and she receives book royalties. She handed over intellectual property rights for a neonatal resuscitation trolley and stepped down as chair for those discussions. The other authors have no declarations of interest.