1 Institute of Reproductive and Child Health, National Health Commission Key Laboratory of Reproductive Health, Peking University School of Public Health, Beijing, China.
2 Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong Province, China.
3 State Key Laboratory of Female Fertility Promotion, Centre for Reproductive Medicine, Department of Obstetrics and Gynaecology, Peking University Third Hospital, Beijing, China jie.qiao@263.net.