1 Department of Obstetrics and Gynaecology, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
2 Department of Obstetrics and Gynaecology, Queen Mary Hospital, Hong Kong, China.
3 Department of Obstetrics and Gynaecology, Kwong Wah Hospital, Hong Kong, China.
4 Shenzhen Key Laboratory of Fertility Regulation, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China.
5 Department of Obstetrics and Gynaecology, School of Clinical Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China. nghye@hku.hk.