Department of Obstetrics and Gynecology;
Peking University First Hospital;
Beijing;
China;
Department of Gynecology;
Fujian Provincial Tumor Hospital;
Fuzhou;
China;
Department of Obstetrics and Gynecology;
The Fifth Hospital of Shijiazhuang;
Shijiazhuang;
China;
Department of Obstetrics & Gynecology;
Beijing Tsinghua Changgung Hospital Medical Center;
Tsinghua University;
Beijing;
China;