1. Department of Cardiology , Army Medical Center of PLA , Chongqing , P.R. China
2. Department of Laboratory Pathology , Unit 32280 of the People’s Liberation Army , Leshan City , Sichuan Province , P.R. China
3. Department of Obstetrics and Gynecology , Army Medical Center of PLA , Chongqing , P.R. China
4. Department of Health Statistics , Army Military Medical University , Chongqing , P.R. China