1. Department of Obstetrics and Gynecology University Medical Center Groningen, University of Groningen Groningen The Netherlands
2. Department of Epidemiology University Medical Center Groningen, University of Groningen Groningen The Netherlands
3. Department of Obstetrics and Gynecology Amsterdam University Medical Centers, University of Amsterdam Amsterdam The Netherlands
4. Department of Obstetrics and Gynecology Leiden University Medical Center Leiden The Netherlands
5. Department of Obstetrics and Gynecology Ikazia Hospital Rotterdam The Netherlands
6. Amsterdam Reproduction and Development Research Institute Amsterdam The Netherlands