Professor of Reproductive Medicine, University of Utrecht, The Netherlands. Chair Department of Reproductive Medicine & Gynecology, UniversityMedicalCenter, Utrecht (since 2004).
Former Professor of Reproductive Endocrinology and director Center of Reproductive Medicine, Erasmus Medical Center, Rotterdam, The Netherlands (1996-2003). Saal van Zwanenberg Professor, of Free University, Brussels, Belgium (2003-2008); Visiting Professor, Stanford School of Medicine, Palo Alto, California, USA (1993-1995); Fulbright post-doctoral Scholar, University of California, San Diego, California (1987-1988). Visiting Professor University of Siena, Italy (2011-); Visiting Professor, University Southampton, UK (2010-); Visiting Professor University of Adelaide, Australia (9 December 2013)
Former Editor-in-Chief ‘Human Reproduction Update’ (2001-2007). Major research interest; pathophysiology of human ovarian function..
Chair WHO steering committee infertility guidelines (2011 - )
Senior Editor: Reporductive Biomedicine Online (2015 - )