Improved survival but increasing bronchopulmonary dysplasia among infants born at 22–23 weeks’ gestation: A 20-year large cohort study

Hidehiko Nakanishi, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan; Masayo Kokubo, Nagano Children's Hospital, Azumino, Nagano, Japan; Tetsuya Isayama, National Center for Child Health and Development, Setagaya-ku, Tokyo, Japan; Shinya Hirano, Osaka Women's and Children's Hospital, Izumi, Osaka, Japan; Kusuda Satoshi, Neonatal Research Network of Japan, Taito, Tokyo, Japan