[1] Univ Nottingham, Royal Derby Hosp, Dept Obstet & Gynecol, Derby, England
[2] Assiut Univ, Dept Obstet & Gynecol, Assiut, Egypt
[3] Univ British Columbia, Dept Obstet & Gynecol, Vancouver, BC, Canada
[4] Derby Teaching Hosp NHS Fdn Trust, Derby, England