P Hu1, Y Wang1, R Sun2, L Cao3, X Chen4, C Liu1, C Luo1, D Ma1, W Wang5, X Fu5, W Shi5, S Yi5, K Zhang6, H Liu7, Z Xu8. 1. State Key Laboratory of Reproductive Medicine, Department of Prenatal Diagnosis, Obstetrics and Gynecology Hospital Affiliated to Nanjing Medical University, Nanjing 210029. China. 2. Department of Laboratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing. China. 3. Department of Ultrasound, Obstetrics and Gynecology Hospital Affiliated to Nanjing Medical University, Nanjing 210029. China. 4. Department of Gynecology and Obstetrics, West China Second Hospital, Sichuan University, 20 Renminnan Road, Chengdu, Sichuan 610041. China. 5. Institute for Genomic Medicine and Shiley Eye Institute, University of California San Diego, La Jolla, CA 92093. United States. 6. Institute for Genomic Medicine, University of California San Diego, La Jolla, California 92093. United States. 7. Department of Gynecology and Obstetrics, West China Second Hospital, Sichuan University, Chengdu, Sichuan. China. 8. State Key Laboratory of Reproductive Medicine, Department of Prenatal Diagnosis, Obstetrics and Gynecology Hospital Affiliated to Nanjing Medical University, Nanjing. China.