Saving lives, improving mothers' care: Surveillance of maternal deaths in the UK 2011-13 and lessons learned to inform maternity care from the UK and Ireland. Confidential enquiries into maternal deaths and morbidity 2009-13 - Knight, M; Tuffnell, D; Kenyon, S; Shakespeare, J; Gray, R; Kurinczuk, J (National Perinatal Epidemiology Unit, University of Oxford, 2015)