1 Department of Obstetrics and Gynaecology, Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. l.s.bleker@amc.uva.nl.
2 Department of Obstetrics and Gynaecology, Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. s.r.derooij@amsterdamumc.nl.
3 Department of Obstetrics and Gynaecology, Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. t.j.roseboom@amsterdamumc.nl.