About the Authors

Pia Hardelid

Affiliation Centre for Paediatric Epidemiology and Biostatistics, University College London Institute of Child Health, London, United Kingdom

Jonathan Davey

Affiliation Centre for Paediatric Epidemiology and Biostatistics, University College London Institute of Child Health, London, United Kingdom

Nirupa Dattani

Affiliation Centre for Paediatric Epidemiology and Biostatistics, University College London Institute of Child Health, London, United Kingdom

Ruth Gilbert

r.gilbert@ucl.ac.uk

Affiliation Centre for Paediatric Epidemiology and Biostatistics, University College London Institute of Child Health, London, United Kingdom

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: RG PH ND JD. Analyzed the data: PH JD ND. Wrote the paper: PH RG. Critically reviewed the manuscript: RG PH JD ND.