1. Murdoch Children's Research Institute, Parkville, Victoria 3052, Australia
2. Research Unit on Gynaecology and Obstetrics, Institute of Clinical Research, University of Southern Denmark, 5000 Odense C, Denmark
3. Institute for Clinical Medicine, Aarhus University, 8200 Aarhus N, Denmark
4. Department of Obstetrics and Gynaecology, Aarhus University Hospital, 8200 Aarhus N, Denmark
5. Telethon Kids Institute, The University of Western Australia, Subiaco, Western Australia 6008, Australia
6. Department of Clinical Epidemiology, Aarhus University Hospital, 8200 Aarhus N, Denmark
7. Department of Paediatrics, University of Melbourne, Parkville, Victoria 3052, Australia and
8. Department of Paediatrics, Monash University, Clayton, Victoria 3068, Australia