Affiliation: | 1. Department of Public Health, University of the West of England, Stapleton, Bristol, UK;2. Department of Public Health Medicine, Bristol Primary Care Trust, King Square, Bristol, UK;3. South West Congenital Anomaly Register, Institute of Child Life and Health, Level D, St Michael's Hospital, Bristol, UK;4. Department of Fetal Medicine and Obstetrics, St Michael's Hospital, Bristol, UK |