[1] Hunan Key Lab Res & Dev Novel Pharmaceut Preparat, Leifeng Rd 1501, Changsha 410219, Peoples R China
[2] Changsha Med Univ, Sch Stomatol, Changsha 410219, Peoples R China
[3] Hunan Prov Maternal & Child Hlth Hosp, Dept Gynaecol & Obstet, Changsha 410219, Peoples R China
[4] Changsha Med Univ, Sch Publ Hlth, Changsha 410219, Peoples R China