1. Department of Pharmacoepidemiology and Pharmacoeconomics; University of Groningen; Groningen The Netherlands
2. Paediatric Department; Hospital Lillebaelt; Kolding Denmark
3. Department of Obstetrics and Women's Diseases; Poznan University of Medical Sciences; Poznań Poland
4. Congenital Anomaly Register and Information Service for Wales; Singleton Hospital; Swansea UK