1. Division of Gynecological Endocrinology and Reproductive Medicine, Women's University Hospital, Inselspital, University of Bern, Bern, Switzerland.
2. PharmacoEpidemiology and Drug Safety Research Group, Department of Pharmacy, and PharmaTox Strategic Research Initiative, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway.
3. Lucerne Cantonal Hospital, Women's Hospital, Lucerne, Switzerland.
4. Oslo Centre for Biostatistics and Epidemiology, Oslo University Hospital, Oslo, Norway.