1. Department of Obstetrics, Women and Children’s Hospital of Chongqing Medical University, Chongqing 401147, China
2. Department of Obstetrics, Chongqing Women and Children's Health Center, Chongqing 401147, China
3. Department of Gynaecology and Obstetrics, Chengdu Women’s and Children’s Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 611731, China
4. State Key Laboratory of Maternal and Fetal Medicine of Chongqing Municipality, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China