1. Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA;
2. Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA;
3. Department of Obstetrics and Gynecology, Chulalongkorn University, Bangkok, Thailand;
4. Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand