Footnotes

• Contributors All authors drafted and revised the manuscript. All authors were involved in the PLUTO trial.

• Funding Well-being of Women and the Hannah Eliza Guy Charity (Birmingham Children's Hospital Charity) funded the original commencement of the trial at Birmingham Women's Hospital NHS Trust in 2005 and then 2008–2012 was funded by the NIHR HTA programme. During the lifetime of this work Dr Morris was also funded by a MRC/RCOG Clinical Research Training Fellowship and a NIHR Clinical Lectureship. Other researchers were funded by the Mary Crosse Fellowship (Birmingham Women's Hospital NHS Foundation Trust Research and Development) and a MRC Midlands Hub for Trials Methodology Research at the University of Birmingham (Medical Research Council Grant ID G0800808).

• Competing interests Professor Mark Kilby (Professor of Fetal Medicine) was the Chief Investigator for the PLUTO study. Dr Jane Daniels is Deputy Director Birmingham Clinical Trials Unit and was involved in the PLUTO trial design and management. Professor Jon Deeks is Professor of Biostatistics and Director of the Birmingham Clinical Trials Unit and was involved in this capacity in the PLUTO study. Dr Katie Morris was the research fellow for the trial. Professor David Field was a member of the PLUTO Trial Steering Committee.

• Provenance and peer review Commissioned; externally peer reviewed.