1. Department of Fetal-Maternal Medicine; Nagara Medical Center; Gifu Japan
2. Perinatal Care Center; Yamaguchi University Hospital; Ube Japan
3. Maternal and Perinatal Care Center; Seirei Hamamatsu General Hospital; Hamamatsu Japan
4. The Department of Perinatology; National Cerebral Cardiovascular Center; Osaka Japan
5. Clinical Research Center; National Center for Child Health and Development; Tokyo Japan
6. Center for Maternal-Fetal and Neonatal Medicine; National Center for Child Health and Development; Tokyo Japan