- Correspondence to Dr Benjamin Saul Raywood Allin, National Perinatal Epidemiology Unit, University of Oxford, Richard Doll Building, Old Road Campus, Headington, Oxford OX3 7LF, UK;
- Received February 21, 2017
- Revised May 26, 2017
- Accepted June 1, 2017
- First published August 7, 2017.
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