1. Department of Obstetrics and GynaecologyPeking Union Medical College Hospital Beijing China
2. Department of Obstetrics and GynaecologyTianjin Medical University General Hospital Tianjin China
3. Department of Obstetrics and GynaecologyTianjin Port Hospital Tianjin China
4. National Institute for Viral Disease Control and Prevention Beijing China
5. Division of Medical Biology, Key Laboratory of Protein Engineering and Drug Development of Hainan Haikou Hainan China
6. SR Life Sciences Institute Clarksburg MD