Author affiliations:
  1. Institute of Applied Health Research, University of Birmingham, Birmingham, United Kingdom, B15 2TT.
  2. Division of Birth Cohort Study, Guangzhou Women and Children’s Medical Centre, Guangzhou Medical University, Guangzhou, China, 510500.
  3. Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom, G12 8TA
  4. Geneva School of Economics and Management, Research Centre for Statistics, University of Geneva, Switzerland