1. Academic Medical Center; Department of Obstetrics and Gynaecology; Meibergdreef 9 Amsterdam Netherlands 1105 AZ
2. Academic Medical Center, University of Amsterdam; Department of Clinical Epidemiology, Biostatistics and Bioinformatics; P.O. Box 22700 Amsterdam Netherlands 1100 DE
3. Academic Medical Center Amsterdam; Gynaecology; Meibergdreef 9 Amsterdam Netherlands 1105 AZ
4. Monash University; Department of Obstetrics and Gynaecology; 246 Clayton Road Clayton Victoria Australia 3168