1. Department of Clinical Epidemiology, Clinical Research Center, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning 110004, P. R. China
2. Clinical Research Center, Shengjing Hospital of China Medical University, Shenyang, China
3. Department of Cardiology, Shengjing Hospital of China Medical University, Shenyang, China
4. Department of Obstetrics and Gynecology, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning 110004, P. R. China