1. Foshan Institute of Fetal Medicine, Southern Medical University Affiliated Maternal and Child Health Hospital of Foshan, Foshan, Guangdong, China
2. Department of Obstetrics, Southern Medical University Affiliated Maternal and Child Health Hospital of Foshan, Foshan, Guangdong, China
3. Medical Administration Division, Affiliated Huadu Hospital, Southern Medical University (People’s Hospital of Huadu District), Guangzhou, Guangdong, China