1. Department of Obstetrics and Gynecology, Hue University of Medicine and Pharmacy, Hue University, Hue City, Vietnam.
2. Center for Reproductive Endocrinology and Infertility, Hue University Hospital, Hue University, Hue City, Vietnam.
3. Department of Public Health, Hue University of Medicine and Pharmacy, Hue University, Hue City, Vietnam.
4. Department of Obstetrics and Gynecology, Hue Central Hospital, Hue City, Vietnam.