1. a Thai Red Cross Society , 1871 Rama IV Road, Bangkok , 10330 , Thailand
2. b Program on Population, East-West Center , 1777 East-West Road, Honolulu , Hawaii , 96848 , USA
3. c Family Planning Unit, Department of Obstetrics and Gynaecology , Faculty of Medicine, Khon Kaen University , Khon Kaen , 40002 , Thailand