- Correspondence to Sophie Bennett, UCL Institute of Child Health, London WC1N 1EH, UK;
- Received September 2, 2014
- Revised February 13, 2015
- Accepted February 16, 2015
- First published March 17, 2015.
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Files in this Data Supplement:
- Data supplement 1 - Online supplement
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.