1. Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, Shenzhen 518053, China
2. Department of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
3. Department of Urology, Daping Hospital, Army Medical University, Chongqing 400042, China
4. Department of Andrology, Bonn University Hospital, Campus-Venusberg 1, 53127 Bonn, Germany