1. Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania; Division of Neonatology and Center for Pediatric Clinical Effectiveness; 34th Street and Civic Center Boulevard Philadelphia Pennsylvania USA 19104
2. Children's Hospital of Philadelphia; Division of Pulmonary Medicine; Philadelphia USA
3. Guangdong General Hospital, Guangdong Academy of Medical Sciences; Department of Pediatrics; 106 Zhongshan Second Road Guangzhou Guangdong China 510080
4. Royal Jubilee Maternity Service; Regional Neonatal Intensive Care Unit; Royal Maternity Hospital Grosvenor Road Belfast Northern Ireland UK BT12 6BB
5. University of Pennsylvania School of Medicine; Department of Pediatrics; Children's Hospital of Philadelphia South 34th Street & Civic Center Blvd Philadelphia Pennsylvania USA 19104
6. McMaster University; Department of Clinical Epidemiology and Biostatistics; Hamilton Ontario Canada