1. Department of Biostatistics, Faculty of Fundamental Sciences, The Hanoi University of Public Health, Hanoi, Vietnam
2. Department of Epidemiology, Faculty of Fundamental Sciences, The Hanoi University of Public Health, Hanoi, Vietnam
3. Department of Scientific Research, Hanoi Obstetrics and Gynaecology Hospital, Hanoi, Vietnam
4. Department of Reproductive Health, Faculty of Social Sciences - Health Education and Behaviour, The Hanoi University of Public Health, Hanoi, Vietnam