Footnotes

• Contributors JB had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Funding: GBH, MZN, RJB, JB Concept and design: MZN, GBH, JB, AML, Boyle,.Acquisition, analysis, or interpretation of data: JB, MZN, AML, BG, ZMC, KM Drafting of the manuscript: JB, MZN, AML, BG, ZMC, KM, RJB, GBH. Critical revision of the manuscript for important intellectual content: JB, MZN, AML, BG, ZMC, KM, RJB, GBH. Statistical analysis: MZN, AML, JB. Administrative, technical, or material support: MZN, AML, BG, ZMC, KM, RJB. Supervision: JB, MZN and AML.

• Funding This study was funded by UK Research and Innovation (Innovate UK, Biomedical Catalyst 2018 Round two, Ref no 105292) and NIHR Imperial Biomedical Research Centre (FR400). The study was supported by Ingenza Limited, Roslin Innovation Centre, Roslin, EH25 9RG and the English National institute for Health Research (NIHR) Medtech and In vitro diagnostics Co-operative (MICs) program.

• Disclaimer The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.

• Competing interests JB is supported by the Imperial Biomedical Research Centre, Imperial College Healthcare NHS Trust, to run neonatal research studies. RJB declares receiving consultancy payments from Cochrane, Wiley and sons, the British Society for Allergy and Clinical Immunology and Prota Therapeutics and expert witness fees for cases related to anaphylaxis and infant nutrition claims, all unrelated to this study. The other authors have no financial or ethical conflicts of interest relevant to this article to declare. Ingenza Limited provided the pH testing kits for the study and participated in the trial management group meetings and reviewed the draft study manuscript.

• Provenance and peer review Not commissioned; externally peer reviewed.