[1] Chinese Univ Hong Kong, Prince Wales Hosp, Dept Microbiol, Fac Med, Shatin, Hong Kong, Peoples R China
[2] Chinese Univ Hong Kong, Prince Wales Hosp, Dept Obstet & Gynaecol, Fac Med, Shatin, Hong Kong, Peoples R China
[3] Queen Elizabeth Hosp, Dept Obstet & Gynaecol, Kowloon, Hong Kong, Peoples R China
[4] Chinese Univ Hong Kong, Prince Wales Hosp, Dept Anat & Cellular Pathol, Fac Med, Shatin, Hong Kong, Peoples R China
[5] Hong Kong Govt, Dept Hlth, Social Hyg Serv, Hong Kong, Hong Kong, Peoples R China