1. West China Second University Hospital, Sichuan University; Department of Obstetrics and Gynecology; No. 20, Third Section of Ren Min Nan Road Chengdu Sichuan China 610041
2. Karolinska Institute; Department of Medical Epidemiology and Biostatics; Box 281 Stockholm Sweden SE-17177
3. West China Hospital, Sichuan University; Department of Neurology; No. 37, Guo Xue Xiang Chengdu Sichuan China 610041
4. West China Hospital, Sichuan University; Chinese Cochrane Centre, Chinese Clinical Trial Registry, Chinese Evidence-Based Medicine Centre, INCLEN Resource and Training Centre; No. 37, Guo Xue Xiang Chengdu Sichuan China 610041
5. University of Oxford; Cochrane Dementia and Cognitive Improvement Group; John Radcliffe Hospital Level 4, Main Hospital, Room 4401c Oxford Oxfordshire UK OX39DU