[1] Hiroshima Univ, Grad Sch Biomed Sci, Dept Obstet & Gynecol, Hiroshima, Japan
[2] Hiroshima Univ, Grad Sch Biomed Sci, Dept Epidemiol Infect Dis Control & Prevent, Hiroshima, Japan
[3] Hiroshima Prefectural Hosp, Dept Obstet & Gynecol, Hiroshima, Japan