1. Department of Occupational and Environmental HealthDalian Medical UniversityP.R. China
2. Department of NeurosurgeryThe Second Affiliated Hospital, Dalian Medical UniversityP.R. China
3. Department of Obstetrics and GynecologyNo. 210 Hospital of PLAP.R. China
4. Department of Obstetrics and GynecologyGeneral Hospital of Beijing Military CommandP.R. China
5. Department of Radiation OncologyNo. 202 Hospital of PLAP.R. China