1. University of Edinburgh; Centre for Population Health Sciences; Edinburgh UK EH8 9AG
2. University of Auckland; Department of Obstetrics and Gynaecology; Private Bag 92019 Auckland New Zealand 1142
3. 15 Orchard Road Edinburgh UK EH4 2EP
4. Malmö University Hospital; Department of Vascular Diseases; Malmö Sweden S205 02
5. CAPHRI Research School, Maastricht University; Department of Epidemiology; Maastricht Netherlands 6200 MD