1. Fetal Medicine Unit, Department of Obstetrics and Gynaecology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong
2. Fetal Medicine Unit, Department of Obstetrics and Gynaecology, Tuen Mun Hospital, Hong Kong
3. Fetal Medicine Unit, Department of Obstetrics and Gynaecology, Queen Mary Hospital, Hong Kong
4. Fetal Medicine Unit, Department of Obstetrics and Gynaecology, Princess Margaret Hospital, Hong Kong
5. Fetal Medicine Unit, Department of Obstetrics and Gynaecology, Queen Elizabeth Hospital, Hong Kong