Footnotes

• Contributors DW drafted the manuscript and TN helped to plan, edit and research.

• Funding Wellcome Trust (WT106587/Z/14/Z).

• Competing interests None declared.

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

• ↵i This is a composite case experienced by DW. Details have been altered.

• ↵ii Birchley is correct in this sense—all cases that fall above the HT would also sit above the BIT (choices that impose a significant risk of serious harm by definition do not maximally promote the well-being of the child). However, the reverse does not apply.

• ↵iii One example is the difference between oral and intramuscular preparations of vitamin K. Although it appears from epidemiological studies that intramuscular vitamin K is more effective than oral vitamin K in preventing haemorrhagic disease,7 there have been no randomised controlled trials that have looked at this question.4