1. Department of Obstetrics & Gynecology, Tianjin Medical University General Hospital, Tianjin, China
2. Tianjin Key Laboratory of Female Reproductive Health and Eugenics, Tianjin, China
3. Institute of Disaster Medicine, Tianjin University, Tianjin, China
4. Department of Obstetrics, The Second Hospital of Tianjin Medical University, Tianjin, China
5. Department of Obstetrics & Gynecology, Guangdong Province Hospital for Women and Children Healthcare, Guangzhou, China