1 Maternal-Fetal Medicine Research Institute, Department of Obstetrics and Gynaecology, Shenzhen Baoan Women's and Children's Hospital, Shenzhen University, Shenzhen, China; Center for Bioethics, Harvard Medical School, Boston, MA, USA. Electronic address: xiaoyan_chen@hms.harvard.edu.
2 Department of Obstetrics and Gynaecology, Peking University Third Hospital, Beijing, China.
3 Center for Bioethics, Harvard Medical School, Boston, MA, USA; Divison of General Obstetrics and Gynecology, Brigham and Women's Hospital, Boston, MA, USA.
4 Maternal-Fetal Medicine Research Institute, Department of Obstetrics and Gynaecology, Shenzhen Baoan Women's and Children's Hospital, Shenzhen University, Shenzhen, China.