1 Department of Obstetrics and Gynaecology, Schulich School of Medicine and Dentistry, Western University, London, Ont.
2 Department of Pathology and Laboratory Medicine, Western University, London, Ont.; Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ont.
3 Department of Obstetrics and Gynaecology, Stratford General Hospital, Stratford, Ont.
4 Department of Obstetrics and Gynaecology, Schulich School of Medicine and Dentistry, Western University, London, Ont.; Division of Maternal Fetal Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ont.; Children's Health Research Institute, London, Ont.