1 Department of Obstetrics and Gynaecology, Leiden University Medical Centre, 2300RC Leiden, Netherlands; Athena Institute, VU University, Amsterdam, Netherlands. Electronic address: T.H.van_den_Akker@lumc.nl.
2 Departments of Obstetrics and Gynaecology and Health Research Methods, Evidence and Impact, McMaster University, Hamilton, ON, Canada.
3 School of Nursing and Midwifery, College of Health and Medical Sciences, Haramaya University, Harar, Ethiopia.
4 National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
5 Division of Mental and Physical Health, Norwegian Institute of Public Health, Bergen, Norway.
6 National Centre for Disease Prevention and Health Promotion, Istituto Superiore di Sanità, Italian National Health Institute, Rome, Italy.