[1] Chinese Univ Hong Kong, Jockey Club Sch Publ Hlth & Primary Care, Shatin, Hong Kong, Peoples R China
[2] Queen Mary Univ London, Barts & London Sch Med & Dent, London, England
[3] Univ Oxford, Nuffield Dept Populat Hlth, Oxford, England
[4] Chinese Univ Hong Kong, Dept Obstet & Gynaecol, Shatin, Hong Kong, Peoples R China
[5] Tuen Mun Hosp, Dept Obstet & Gynaecol, Tuen Mun, Hong Kong, Peoples R China
[6] Chinese Univ Hong Kong, Shenzhen Res Inst, Shenzhen, Peoples R China
[7] Chinese Univ Hong Kong, Prince Wales Hosp, Jockey Club Sch Publ Hlth & Primary Care, Shatin, 4-F Sch Publ Hlth Bldg, Hong Kong, Peoples R China