1. Department of Epidemiology& Biostatistics, Hanoi University of Public Health, Hanoi, Vietnam
2. Food Safety Management Board, Bac Ninh provincial People’s Committee, Bac Ninh, Vietnam
3. Department of Obstetrics and Gynecology, Bach Mai Hospital, Hanoi, Vietnam
4. Department of Training, National Hospital for Obstetrics and Gynecology, Hanoi, Vietnam