[1] Radboud Univ Nijmegen, Med Ctr, NL-6500 HB Nijmegen, Netherlands
[2] Radboud Univ Nijmegen, Arnhem, Netherlands
[3] Univ Auckland, Dept Obstet & Gynaecol, Auckland 1, New Zealand
[4] Univ Auckland, Sch Populat Hlth, Epidemiol & Biostat Sect, Auckland 1, New Zealand
[5] Natl Inst Clin Studies NHMRC, Australian Satellite Cochrane EPOC Grp, Melbourne, Vic, Australia
[6] Natl Womens Hosp, Auckland, New Zealand
[7] Univ Tesside, Middlesbrough, Guisborough, England
[8] S Cleveland Hosp, Middlesbrough, Guisborough, England
[9] Univ Maastricht, Fac Med, Maastricht, Netherlands
[10] Maxima Med Ctr, Veldhoven, Netherlands