1. Department of Obstetrics & Gynaecology, Kwong Wah Hospital, Hong Kong Special Administrative Region, China;
2. Department of Obstetrics & Gynaecology, Queen Mary Hospital, Hong Kong Special Administrative Region, China;
3. Fetal Medicine Centre, Paramount Medical Centre, Hong Kong Special Administrative Region, China;
4. Department of Paediatrics, Kwong Wah Hospital, Hong Kong Special Administrative Region, China;
5. Department of Obstetrics & Gynaecology, The University of Hong Kong, Hong Kong Special Administrative Region, China