1 Center for Reproductive Medicine, Peking University Third Hospital, Haidian District, Beijing, People's Republic of China.
2 Center for Reproductive Medicine, Peking University Third Hospital, Haidian District, Beijing, People's Republic of China; Key Laboratory of Reproductive Genetics (Ministry of Education) and Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.