[1] Univ Hong Kong, Queen Mary Hosp, Dept Obstet & Gynaecol, Hong Kong, Hong Kong, Peoples R China
[2] Univ Hong Kong, Queen Mary Hosp, Dept Pathol, Hong Kong, Hong Kong, Peoples R China
[3] Univ Hong Kong, Queen Mary Hosp, Dept Med, Hong Kong, Hong Kong, Peoples R China
[4] Tsan Yuk Hosp, Dept Prenatal Diag & Counselling, Hong Kong, Hong Kong, Peoples R China