[1] Natl Ctr Child Hlth & Dev, Ctr Maternal Fetal Neonatal & Reprod Med, Dept Obstet Med, Setagaya Ku, Tokyo, Japan
[2] Natl Hosp Org, Tokyo Med Ctr, Dept Gen Internal Med, Meguro Ku, Tokyo, Japan
[3] Tohoku Univ Hosp, Dept Diagnost Radiol, Sendai, Miyagi, Japan
[4] Natl Ctr Child Hlth & Dev, Ctr Maternal Fetal Neonatal & Reprod Med, Setagaya Ku, Tokyo, Japan