[1] Capital Med Univ, Beijing Youan Hosp, Ctr Infect Dis, Beijing 100069, Peoples R China
[2] China CDC, Natl Ctr Women & Childrens Hlth, Beijing 100081, Peoples R China
[3] Beijing Ctr Prevent Med Res, Beijing 100013, Peoples R China
[4] Capital Med Univ, Beijing Youan Hosp, Dept Gynecol, Beijing 100069, Peoples R China
[5] Zhejiang Univ, Sch Med, Womens Hosp, Hangzhou 310006, Zhejiang, Peoples R China