1. Department of Fetal-Maternal Medicine; Nagara Medical Center; Gifu Japan
2. Center of Maternal-Fetal, Neonatal and Reproductive Medicine; National Center for Child Health and Development; Tokyo Japan
3. Department of Maternal Fetal Medicine; Osaka Women's and Children Hospital; Izumi Japan
4. Department of Perinatology, Maternal and Perinatal Care Center; Seirei Hamamatsu General Hospital; Hamamatsu Japan
5. Department of Obstetrics; Miyagi Children's Hospital; Sendai Japan
6. Department of Obstetrics and Gynecology; Toho University Omori Medical Center; Tokyo Japan