Department of Pediatrics, Taitung MacKay Memorial Hospital, Taitung County, Taiwan; Division of Neonatology, Department of Pediatrics, MacKay Children's Hospital, Taipei City, Taiwan. Department of Pediatrics, Hsinchu MacKay Memorial Hospital, Hsinchu City, Taiwan. Division of Neonatology, Department of Pediatrics, MacKay Children's Hospital, Taipei City, Taiwan; Department of Medicine, MacKay Medical College, New Taipei City, Taiwan. Division of Neonatology, Department of Pediatrics, MacKay Children's Hospital, Taipei City, Taiwan. Division of Neonatology, Department of Pediatrics, MacKay Children's Hospital, Taipei City, Taiwan; Department of Medicine, MacKay Medical College, New Taipei City, Taiwan; MacKay Junior College of Medicine, Nursing and Management, New Taipei City, Taiwan. Electronic address: jhchang90@yahoo.com.tw.