[1] Univ Glasgow, Dept Med, Glasgow G12 8QQ, Lanark, Scotland
[2] United Lincolnshire Hosp, Dept Haematol, Lincoln, England
[3] Glasgow Royal Infirm, Dept Haematol, Glasgow, Lanark, Scotland
[4] Leeds Teaching Hosp, Dept Obstet & Gynaecol, Leeds, W Yorkshire, England
[5] Royal Liverpool Hosp, Dept Haematol, Liverpool, Merseyside, England
[6] Univ Hosp Bristol, Dept Haematol, Bristol, Avon, England
[7] Cardiff & Vale Univ Hlth Board, Dept Obstet, Cardiff, S Glam, Wales
[8] Derby Teaching Hosp, Dept Haematol, Derby, England
[9] Oxford Univ Hosp, Dept Haematol, Oxford, England