1. Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, People's Republic of China.
2. Department of Obstetrics and Gynecology, Center of Reproductive Medicine, Peking University Third Hospital, Beijing, People's Republic of China.
3. Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, People's Republic of China.
4. Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, People's Republic of China.