1. Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China
2. Key Laboratory of Reproductive Endocrinology, Shandong University, Ministry of Education, and National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Jinan, China
3. Department of Obstetrics and Gynecology, the Second Hospital of Shandong University, Jinan, China
4. Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, and Shanghai Key Laboratory of Assisted Reproduction and Reproductive Genetics, Shanghai, China
5. Center for Reproductive Medicine, Qilu Hospital of Shandong University, Jinan, China
6. Department of Biostatistics, Yale University School of Public Health, New Haven, Connecticut
7. Department of Obstetrics and Gynecology, Penn State College of Medicine, Hershey, Pennsylvania