1. Primary Care Research Centre, School of Primary Care, Population Sciences and Medical Education University of Southampton, Aldermoor Health Centre Southampton UK
2. School of Nursing and Midwifery, College of Health and Medical Sciences Haramaya University Harar Ethiopia
3. Department of Obstetrics and Gynecology Leiden University Medical Center Leiden the Netherlands
4. Athena Institute Vrije Universiteit Amsterdam Amsterdam the Netherlands
5. National Perinatal Epidemiology Unit University of Oxford Oxford UK
6. IRD, Inserm, Ceped Université Paris Cité Paris France