1. Department of Social Medicine; National Center for Child Health and Development; Tokyo Japan
2. Center of Maternal-Fetal, Neonatal and Reproductive Medicine; National Center for Child Health and Development; Tokyo Japan
3. Collaborative Departments of Advanced Pediatric Medicine; Graduate School of Medicine; Tohoku University; Miyagi Japan
4. Department of Obstetrics & Gynecology; School of Medicine; University of Toyama; Toyama Japan
5. Maternal and Perinatal Care Center; Oita Prefectural Hospital; Oita Japan
6. Department of Global Health Promotion; Tokyo Medical and Dental University; Tokyo Japan