[1] Univ Amsterdam, Acad Med Ctr, Ctr Reprod Med, Dept Obstet & Gynaecol, NL-1105 AZ Amsterdam, Netherlands
[2] Univ Amsterdam, Acad Med Ctr, Dept Clin Epidemiol & Biostat, NL-1105 AZ Amsterdam, Netherlands
[3] Maxima Med Ctr, Dept Obstet & Gynaecol, Veldhoven, Netherlands
[4] Onze Lieve Vrouw Hosp, Dept Obstet & Gynaecol, Amsterdam, Netherlands
[5] Univ Med Ctr, Erasmus MC, Dept Publ Hlth, Rotterdam, Netherlands
[6] Vrije Univ Amsterdam, Med Ctr, Dept Obstet & Gynaecol, Amsterdam, Netherlands