- Correspondence to Professor Marian Knight, National Perinatal Epidemiology Unit, University of Oxford, Oxford, OX3 7LF, UK;
- Received October 27, 2017
- Revised November 15, 2017
- Accepted November 23, 2017
- First published December 5, 2017.
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.