[1] YAMAGATA UNIV,DEPT OBSTET & GYNECOL,YAMAGATA 990,JAPAN
[2] OSAKA UNIV,DEPT OBSTET & GYNECOL,OSAKA,JAPAN
[3] TEIKYO UNIV,DEPT OBSTET & GYNECOL,TOKYO 173,JAPAN
[4] KYORIN UNIV,DEPT OBSTET & GYNECOL,MITAKA,TOKYO 181,JAPAN
[5] UNIV TOKYO,DEPT OBSTET & GYNECOL,TOKYO 113,JAPAN