[1] Univ Amsterdam, Acad Med Ctr, Dept Obstet & Gynaecol, Ctr Reprod Med, NL-1105 AZ Amsterdam, Netherlands
[2] Univ Amsterdam, Acad Med Ctr, Dept Clin Epidemiol Biostat & Bioinformat, NL-1105 AZ Amsterdam, Netherlands
[3] McMaster Univ, Dept Obstet & Gynaecol, Hamilton, ON, Canada
[4] Maastricht Univ, Med Ctr, Dept Obstet & Gynaecol, Maastricht, Netherlands
[5] Deventer Hosp, Dept Obstet & Gynaecol, Deventer, Netherlands
[6] Med Univ Warsaw, Dept Obstet & Gynaecol, Warsaw, Poland
[7] Univ Hong Kong, Dept Obstet & Gynaecol, Hong Kong, Hong Kong, Peoples R China
[8] Univ Gothenburg, Sahlgrenska Acad, Dept Obstet & Gynaecol, Gothenburg, Sweden