[1] AMC, Gynaecol & Obstet, Amsterdam, Netherlands
[2] AMC, Dept Clin Epidemiol Bioinformat & Biostat, Amsterdam, Netherlands
[3] Vrije Univ Amsterdam Med Ctr, Dept Obstet & Gynaecol, Amsterdam, Netherlands
[4] AMC, Dept Med Informat, Amsterdam, Netherlands
[5] Robinson Inst, Sch Paediat & Reprod Hlth, Adelaide, SA, Australia