1. Cardiovascular Epidemiology Unit, Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom.
2. Homerton College, Hills Road, University of Cambridge, Cambridge, United Kingdom.
3. Department of Obstetrics & Gynecology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina.
4. Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina.
5. Department of Maternal and Child Health, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina.