1. Department of Maternity, General Hospital of Shenyang Military Area Command, Shenyang, Liaoning 110016, P.R. China
2. Department of Oncology, General Hospital of Shenyang Military Area Command, Shenyang, Liaoning 110016, P.R. China
3. Department of Neurology, General Hospital of Shenyang Military Area Command, Shenyang, Liaoning 110016, P.R. China
4. Department of Cardiothoracic Surgery, General Hospital of Shenyang Military Area Command, Shenyang, Liaoning 110016, P.R. China