[1] Univ Amsterdam, Acad Med Ctr, Ctr Reprod Med, NL-1012 WX Amsterdam, Netherlands
[2] Univ Amsterdam, Acad Med Ctr, Dept Clin Epidemiol & Biostat, NL-1012 WX Amsterdam, Netherlands
[3] Univ Amsterdam, Acad Med Ctr, Dept Obstet & Gynaecol, NL-1012 WX Amsterdam, Netherlands
[4] Onze Lieve Vrouw Hosp, Dept Obstet & Gynaecol, Amsterdam, Netherlands