1. Department of Obstetrics and GynaecologyMuhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
2. Department of Women's and Children's HealthInternational Maternal and Child Health, Uppsala University, Uppsala, Sweden
3. Department of Epidemiology and BiostatisticsSchool of Public Health and Social Sciences, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
4. Department of Public Health and General PracticeNorwegian University of Science and Technology, Trondheim, Norway