About the Authors

Debbie A Lawlor

To whom correspondence should be addressed. E-mail: d.a.lawlor@bristol.ac.uk

Affiliation Department of Social Medicine, University of Bristol, Bristol, United Kingdom

Abigail Fraser

Affiliation Department of Social Medicine, University of Bristol, Bristol, United Kingdom

Shah Ebrahim

Affiliation Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom

George Davey Smith

Affiliation Department of Social Medicine, University of Bristol, Bristol, United Kingdom

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

DAL, SE, and GDS designed the study. DAL analyzed the data and enrolled patients. All authors contributed to writing the paper. AF made a substantial contribution to interpreting results.