1. School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Polwarth Building, Aberdeen, UK
2. Centre for Reproductive Medicine, Academic Medical Centre, Meibergdreef 9, Amsterdam, The Netherlands
3. Institute of Applied Health Sciences, University of Aberdeen, Polwarth Building, Aberdeen, UK
4. Medical Statistics Team, Institute of Applied Health Sciences, University of Aberdeen, Polwarth Building, Aberdeen, UK