[1] Univ Hong Kong, Dept Community Med, Hong Kong, Hong Kong, Peoples R China
[2] Univ Hong Kong, Unit Behav Sci, Hong Kong, Hong Kong, Peoples R China
[3] Isfahan Univ Med Sci, Sch Publ Hlth, Dept Epidemiol & Biostat, Esfahan, Iran
[4] Family Planning Assoc, Hong Kong, Hong Kong, Peoples R China