[1] Univ Birmingham, Sch Clin & Expt Med, Birmingham Womens Hosp, Obstet & Gynaecol, 3rd Floor,Metchley Pk Rd, Birmingham B15 2TG, W Midlands, England
[2] Birmingham Womens Hosp, Obstet & Gynaecol & Clin Epidemiol, Birmingham, W Midlands, England
[3] Birmingham Womens Hosp, WHO Collaborating Ctr Res Synth Reprod Hlth, Birmingham, W Midlands, England
[4] Birmingham Womens Hosp, Res, Birmingham, W Midlands, England
[5] Birmingham Womens Hosp, Res, Birmingham, W Midlands, England