[1] Univ Groningen, Univ Med Ctr Groningen, Dept Obstet & Gynecol, NL-9700 RB Groningen, Netherlands
[2] Onze Lieve Vrouw Hosp, Dept Obstet & Gynecol, Amsterdam, Netherlands
[3] VieCuri Med Ctr Noord Limburg, Dept Obstet & Gynecol, Venlo, Netherlands
[4] Diaconessenhuis, Dept Obstet & Gynecol, Leiden, Netherlands
[5] Flevoziekenhuis, Dept Obstet & Gynecol, Almere, Netherlands
[6] Maxima Med Ctr, Dept Obstet & Gynecol, Veldhoven, Netherlands
[7] Jeroen Bosch Ziekenhuis, Dept Obstet & Gynecol, Den Bosch, Netherlands
[8] Meander Med Ctr, Dept Obstet & Gynecol, Amersfoort, Netherlands
[9] Med Ctr Leeuwarden, Dept Obstet & Gynecol, Leeuwarden, Netherlands
[10] Deventer Ziekenhuis, Dept Obstet & Gynecol, Deventer, Netherlands
[11] Univ Amsterdam, Acad Med Ctr, Dept Obstet & Gynecol, NL-1105 AZ Amsterdam, Netherlands
[12] Univ Groningen, Univ Med Ctr Groningen, Dept Epidemiol, NL-9700 RB Groningen, Netherlands