1. Department of Obstetrics and Gynaecology, University of Hong Kong, Queen Mary Hospital, Hong Kong;
2. Shenzhen Key Laboratory of Fertility Regulation, Reproductive Medicine Center, The University of Hong Kong – Shenzhen Hospital, Shenzhen, PR China;
3. Department of Women’s and Children’s Health, Division of Obstetrics and Gynaecology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden