1. Departments of Obstetrics and Gynecology; David Geffen School of Medicine at UCLA; University of California; Los Angeles CA USA
2. Kaiser Permanente; Los Angeles Medical Center; Los Angeles CA USA
3. MRC Centre for Reproductive Health; The University of Edinburgh; The Queen's Medical Research Institute; Edinburgh UK
4. School of Women's and Children's Health; Royal Hospital for Women; University of New South Wales; Randwick NSW Australia